.    DEPARTMENT    OF   AGRICULTURE. 

BUREAU  OF  ANIMAL  INDUSTRY— BULLHTIN  No.  O' 

I).  E.  SALMON,  D.  V.  M.,  Chibf  of  Bureau. 


FOOT-ROT  OF  SHEEP 

ITS  XATURE.  CAI'SE,  .\\7)  TREATMENT. 


JOHN    R.  MOHLER,  V.  M.  D., 
Chief  of  Pathological  Division ,  Bureau  of  Anitnal  Industry, 


AND 


HENRY   J.  WASHBURN,  I).  V.  S.. 
Acting  Assistant  Chief  of  Pathological  Division,  Bureau  of  Animal  Industry. 


WASHINGTON:  . 

(ioVKKXMKXT     PRINTIX(;     OF  PICK. 

1904. 


or(;anization  of  the  bureau  of  animal  industry. 


Chief:  D.  E.  Salmon,  D.  Y.  M. 
Assistant  chief:  A.  D.  Melvin,  D.  V.  S. 
Chief  clerk:  E.  B,  Jones,  LL.  M.,  M.  D. 

Dairy  Divi»ion:  -. ,  chief;  Clarence  B.  Lane,  B.  S.,  assistant  chief. 

Inspection  I}inision:  A.  M.  Farrington,  B.  S.,  D..  V.  M.,  chief. 

(^larnntine  Division:  Richard  W.  Hickman,  Ph.  G.,  V.  M.  D.,  chief. 

Editor:  Georle  Fayette  Thompson,  M.  S. 

yirtist:  "W.  S.  D.  Haines. 

Expert  in  Animal  llusbandrij:  George  M.  Rommel,  B.  S.  A. 

Librarian:  Beatrice  C.  Oberly. 

laboratories. 

Biochemic  Ditnnon:  Marion  Dorset,  M.  D.,  chief. 

Pathological  Division:  John  R.  Mohler,  A.  M.,  V.  M.  D.,  chief;  Henry  J.  Wash- 
burn, D.  V.  S.,  acting  as-sistant  chief. 

Zoological  Division:  Brayton  H.  Ransom,  B.  Sc,  A.  M.,  acting  zoologist. 

experiment  station. 

Superintendent,  E.  0.  Schroeder,  M.  D.  V. ;  expert  assistant,  W.  E.  Cotton. 

inspectors  in  charge. 


Dr.  F.  W.  Ainsworth,  Union  Stock  Yards,  Pitts- 
burg, Pa. 

Dr.  M.  O.  Anderson,  care  Geo.  A.  Hormel  &  Co., 
Austin,  Minn. 

Dr.  Don  C.  Ayer,  Post-Office  Building,  South 
Omaha,  Nebr. 

Dr.  G.  S.  Baker,  6th  and  Townsend  sts.,  San  Fran- 
cisco, Cal. 

Dr.  L.  R.  Baker,  South  St.  Joseph,  Mo.  », 

Dr.  Bovd  Baldwin,  care  Cudany  Bros.,  Cudahy^ 
Wis.  ■ 

Dr.  A.  E.  Behnke,  room  432,  Federal  Building, 
Milwaukee,  Wis. 

Dr.  John  A.  Bell,  Watertown,  N.  Y. 

Dr.  S.  E.  Bennett,  room  338,  Live  Stock  Ex- 
change Building,  Kansas  City,  Kans. 

Dr.  Eli  L.  Bertram,  care  Tri-City  Packing  Co., 
Davenport,  Iowa. 

Dr.  Fred  Braginton.care  Continental  Packing  Co., 
Bloomington,  111. 

Dr.  J.  J.  Brougham,  care  Missouri  Stock  Yards, 
St.  Louis,  Mo. 

Dr.  G.  W.  Butler,  care  Drummond  Bros.,  Eau 
Claire,  Wis. 

Dr.  J.  B.  Clancy,  National  Stock  Yards,  111. 

Dr.  Lowell  Clarke,  room  320,  Quincy  Building, 
Denver,  Colo. 

Dr.  Charles  Cowie,  Ogdensbuig,  N.  Y.      , 

Dr.  David  Cumming,  912  Lapeer  ave.,  Port  Huron, 

.    Mich. 

Dr.  Robert  Darling,  care  Chas.  S.  Hardy,  San 
Diego,  Cal. 

Dr.  E.  T.  Davison,  Rnshville,  Nebr. 

Dr.  J.  F.  Deartman,  Saiilt  Ste.  Marie,  Mich. 

Mr.  Albert  Dean,  room  328,  Stock  Yard  Station,- 
Kansas  City,  Kans. 


Dr.  F.  L.  De  Wolf,  care  Chas.  Wolff  Packing  Co., 
Topeka.  Kans. 

Dr.  Geo.  Ditewig,  care  Union  Stock  Yards,  Cin- 
cinnati, Ohio. 

Dr.  E.  P.  Dowd,  care  White,  Pevey  &  Dexter  Co., 
Worcester,  Ma.ss. 

Dr.  O.  E.  Dyson,  316  Exchange  Building,  Union 
Stock  Yards,  Chicago,  111. 

Dr.  Geo.  C.  Faville,  P.  O.  box  7%,  Norfolk,  Va. 

Dr.  N.  K.  Fegley,  care  Sperry  &  Barnes,  New 
Haven,  Conn. 

Dr.  T.  A.  Geddes,  care  U.  S.  consul,  London,  Eng- 
land. 

Dr.  H.  H.  George,  507  Johnson  St.,  LouLsville,  Ky. 

Dr.  W.  H.  Gibbs,  care  Morton-Gregson  Co.,  Ne- 
braska City,  Nebr. 

Dr.  L.  K.  Green,  care  Hammond,  Standish  &  Co.. 
Detroit,  Mich. 

Dr.  H.  A.  Hedrick,  215  St.  Paul  St.,  Baltimorc7Md. 

Dr.  O:.*.  Hess,  care  Frye-Bruhn  Co.,  Seattle, Wash. 

Mr.  G.  S.  Hickox,  P.  O.  box  1145,  Salt  Lake  City, 
Utah. 

Dr.  A.  A.  Holcombe,  Aurora,  HI. 

Dr.  Julius  Huelsen,  care  Jersey  City  Stock  Yards 
Co.,  Jer.sev  Citv,  N.  J. 

Dr.  F.  W.  Huntington,  U.  S.  customs  office,  G.  T. 
R.  R.  wharf,  Portland,  Me, 

Dr.  Robert  Jay,  care  Jacob  E.  Decker  &  Son, 
Mason  City,  Iowa. 

Dr.  G.  A.  Johnson,  Exchange  Building,  Sioux 
,City,  Iowa. 

Dr.  James  Johnston,  care  U.  S.  consul,  Liverpool, 
England. 

Dr.  J.  S.  Kelly,  care  Blomer  &  Michael  Co., 
Quincv,  111. 

Dr.  F.  D.  Ketchum,  SouthSt.  Paul,  Minn. 


(Continued  on  page  3  of  cover.) 


U.   S.    DEPARTMENT    OF   AGRICULTURE. 

BUREAU  OF  ANIMAL  INDUSTRY— BULLETIN  No.  6}. 
D.  E.  SALMON,  D.  V.  M.,  Chief  of  Bubeau. 


FOOT-ROT  OF  SHEEP: 

ITS  NATURE,  CAUSE,  AND  TREATMENT. 


BY 


JOHN    R.  MOHLER,  V.  M.  D., 
Chief  of  Pathological  Division,  Bureau  of  Animal  Industry , 


AND 


HENRY  J.  WASHBURN,  D.  V.  S., 
Acting  Assistant  Chief  of  Pathological  Division,  Bureau  of  Animal  Industry . 


WASHINGTON: 

GOVERNMENT    PRINTING    OFFICE. 

1904. 


LETTER  OF  TRANSMITTAL 


U.  S.  Department  of  Agriculture, 

Bureau  of  Animal  Industry, 
Washington^  D.  C.^  September  ^7,  190 Ji,. 
Sir:  I  have  the  honor  to  transmit  herewith  a  paper  entitled  "  Foot- 
rot  of  sheep:  Its  nature,  cause,  and  treatment,"  by  John  R.  Mohler, 
V.  M.  D.,  chief,  and  Henry  J.  Washburn,  D.  V.  S.,  acting  assistant 
chief,  of  the  Pathological  Division  of  this  Bureau. 

Owing  to  the  magnitude  of  the  sheep  industry  in  this  country  and 
the  serious  character  of  the  disease  in  question,  it  is  of  prime  economic 
importance  that  our  sheepmen  should  be  in  possession  of  full  infor- 
mation concerning  the  nature,  cause,  and  treatment  of  this  malady. 
The  authors  have  endeavored  to  present  these  matters  in  a  clear  and 
comprehensive  manner  by  means  of  an  analysis  of  the  previous  knowl- 
edge of  the  subject,  supplemented  by  original  investigations  and 
experiments  undertaken  for  this  work. 

Foot-rot  of  sheep,  while  not  usually  fatal  in  its  results,  is  neverthe- 
less a  possible  source  of  great  danger  and  loss  to  sheep  owners  because 
of  its  highly  contagious  nature  and  the  frequent  violence  of  its  out- 
breaks, whereby  the  animals  become  stunted,  owing  to  the  slow, 
protracted  course  of  the  disease;  to  all  of  which  must  be  added  the 
difficulty  of  completely  eradicating  the  virus  from  the  soil  and 
premises. 

In  view  of  these  considerations,  I  recommend  the  publication  of  the 
article  as  Bulletin  No.  63  of  the  Bureau  series. 
Respectfully, 

D.  E.  Salmon,  Chief  of  Bureau. 
Hon.  James  Wilson, 

Secretary  of  Agriculture, 
2 


CONTENTS. 


^  Page. 

Introduction 5 

Name  and  synonyms 5 

Historical  review 7 

Symptoms  and  lesions '. 9 

Course  and  susceptibility 11 

Contagion 12 

Bacteriology 15 

Pathogenesis ^ 19 

Inoculation  of  sheep 19 

Direct,  by  pus  from  affected  foot 20 

Indirect,  by  cultures 21 

Subcutaneous  inoculations 23 

Feeding  experiments 23 

Injection  of  filtrates 24 

Inoculation  of  rabbits 24 

Inoculation  of  mice 25 

Inoculation  of  guinea  pigs 25 

Virulence  for  other  animals 25 

Economic  importance 26 

Differential  diagnosis 29 

Wounds  of  the  feet 29 

Purulent  inflammation  of  the  interdigital  spaces  (fouls) 30 

Stoppage  of  biflex  canal 31 

Suppurative  cellulitis  (cutaneous  abscesses) 32 

Foot-and-mouth  disease 33 

Prevention 34 

Treatment 35 

Bibliography 39 


ILLUSTRATIONS 


Page. 

Fig.  1.  Hoof  showing  effects  of  chronic  foot-rot 10 

Plate  1.  Bacillus  nea-ophorus  from  foot-rot  of  sheep 1  <> 

2.  Fig.  1 — Bacillus  of  necrosis.     Fig.  2 — Necrotic  area  in  Uver  of  rabbit . .        16 

3.  Development  of  colonies  of  Bacillus  necrophorus 16 


FOOT-ROT  OP  SHEEP:  ITS  NATURE,  CAUSE,  AND 

TREATMENT. 


By  John  R.  Mohlbr,  V.  M.  D., 
Chief  of  Pathological  Division,  Bureau  of  Animal  Industry, 

AND 

Henry  J.  Washburn,  D,  V.  S., 
Acting  Assistant  Chief  of  Pathological  Division,  Bureau  of  Animal  Industry. 


INTRODUCTION. 


The  sheep  is  the  natural  host  of  many  species  of  internal  animal  para- 
sites, and  surrounding  it  externall}'  are  numerous  carnivorous  animals 
which  merely  await  a  convenient  opportunity  to  fall  upon  and  devour 
their  helpless  victim.  Contagious  and  infectious  diseases  also  ip\a.y  an 
active  part  in  reducing  the  income  from  the  sheep  industr}-.  The}'  not 
only  destroy  many  valuable  members  of  the  flock,  but,  more  serious  still, 
a  greater  number  than  the  total  of  those  which  actually  succumb  to  the  dis- 
ease will  become  weakened,  debilitated,  and  unthrifty,  and  may  remain 
during  an  entire  season  a  source  of  worry,  discouragement,  and  expense 
to  those  who  had  planned  to  derive  benefit  from  them.  In  this  wa\' 
the  loss  sustained  by  the  owner  and  feeder,  while  not  tangible  enough 
to  be  estimated  accurately,  is  nevertheless  very  considerable.  Among 
the  destructive  communicable  diseases  that  always  run  a  slow  pro- 
tracted course,  and  which  at  times  kill  off  the  sheep,  ma}'  be  mentioned 
helminthiasis  (the  affection  due  to  parasitic  worms),  scabies,  and  foot- 
rot.  These  scourges  are  probably  formidable  to  the  American  shep- 
herd in  the  order  named,  and  in  that  order  destroy  or  lessen  his  receipts 
from  an  otherwise  profitable  industry. 

Although  foot-rot  is  not  so  widely  scattered  among  the  flocks  of 
this  country  as  are  some  other  diseases,  it  is  nevertheless  well-known 
and  greatly  feared  in  many  sheep-raising  and  sheep-feeding  localities, 
and  therefore  it  seems  desirable  to  furnish  those  interested  with  infor- 
mation regarding  the  nature,  cause,  and  treatment  of  this  disease. 

NAME   AND   SYNONYMS. 

For  many  years  writers  on  topics  of  economic  importance  to  live- 
stock owners  have  made  mention  of  troublesome  affections  to  which 

6 


6  BUEEAU    OF   ANIMAL   INDUSTRY. 

the  feet  of  sheep  are  liable,  designating  them  collectively  as  foot-rot. 
Under  this  term  all  varieties  of  lameness,  whatever  the  cause,  were 
described.  As  a  result  much  confusion  followed  and  man}-  contro- 
versies arose  regarding  the  nature  of  the  disease  to  which  the  name 
foot-rot  was  applied.  Some  writers  argued  that  the  disease  was  con- 
tagious, others  claimed  that  it  was  not,  while  still  others  stated  that 
foot-rot  was  merely  a  form  of  foot-and-mouth  disease.  Thus  the  term 
foot-rot  became  ver3^  ambiguous  and  it  was  necessar}-  to  be  familiar 
with  the  views  of  the  individual  writer  in  order  to  know  whether  it 
was  applied  to  the  so-called  beftign  form  of  foot-rot,  to  the  contagious 
form  of  the  disease,  to  wounds  of  the  foot,  to  cutaneous  abscesses,  or 
to  foot-and-mouth  disease.  It  naturally  followed  that  a  writer  describ- 
ing the  first-mentioned  malady  claimed  that  it  was  noncontagious, 
while  another  working  with  the  second  disease  would  assert  its  con- 
tagiousness. It  is  probable  that  the  nomenclature  is  responsible  for 
this  unfortunate  confusion,  and  therefore  it  is  proposed  to  differentiate 
these  diseases  and  to  give  an  appropriate  name  to  each  affection, 
believing  that  there  is  as  much  difference  between  the  so-called  benign 
and  the  contagious  forms  of  foot-rot  as  there  is  between  mycotic 
stomatitis  and  foot-and-mouth  disease.  For  this  reason  the  so-called 
benign  foot-rot,  which  results  from  simple  mechanical  irritation,  will 
be  called  purulent  inflammation  of  the  foot,  or  "fouls,"  while  the 
nomenclature  of  Moore,  "  suppurative  cellulitis,"  is  retained  for  the 
cutaneous  abscesses  inv^olving  the  feet.  For  the  contagious  foot-rot 
is  preserved  the  term  "foot-rot,"  and  by  this  name  we  refer  to  the 
chronic  inflammation  of  the  foot  followed  by  ulceration,  softening  of 
the  hoof,  formation  of  a  fetid,  sticky  discharge,  occasioning  lameness 
and  due  to  the  Bacillus  nec7'ophmnts. 

The  true  foot-rot,  as  last  described,  occurs  in  a  contagious  and  enzootic 
form  among  sheep,  attacking  their  feet  and  spreading  from  one  mem- 
ber of  the  flock  to  another  either  by  direct  or  indirect  transmission. 
We  likewise,  for  the  reasons  mentioned  later  on,  see  no  cause  for  con- 
sidering foot  rot  a  complication  of  foot-and-mouth  disease,  and  these 
two  diseases  are  recognized  by  us  as  individual  specific  affections,  each 
produced  by  an  infectious  principle  and  in  no  waj'^  related  one  to  the 
other. 

English  writers  have  usually  adopted  the  term  "contagious  foot- 
rot  "  in  their  descriptions  of  this  affection.  Those  who  employ  Latin 
names  in  their  theses  on  medical  matters  refer  to  foot-rot  as  "  par- 
onychia ungularis  ovium  maligna,"  and  to  one  conversant  with  this 
language  the  name  proves  helpfully  descriptive.  "  Pietin  contagieux  " 
is  the  name  by  wEich  the  disease  is  designated  b}"  French  authors. 
German  pathologists  seldom  refer  to  the  malady  except  in  articles 
devoted  to  a  discussion  of  its  relation  to  contagious  foot-and-mouth 
disease  as  seen  in  sheep.     When  they  require  a  specific  name  for  the 


FOOT-ROT   OF    SHEEP.  ^  .     7 

disease,  one  wholly  independent  of  foot-and-mouth  disease,  they  employ 
the  excellent  term  "bOsartige  Klauenseiiche  derSchafe." 

Under  these  names  the  troublesome  affection  has  been  universally 
recognized  in  veterinary  literature,  and,  although  it  hardly  seems  to 
have  attracted  the  attention  which  its  destiuctive  character  deserves, 
the  general  descriptions  of  the  lesions  of  the  disease  have  been  remark- 
abl}'  harmonious. 

HISTORICAL   REVIEW. 

Foot-rot  was  first  described  by  Chabert  in  the  year  1791  as  existing 
north  of  the  Pyrenees  on  the  banks  of  the  Gironde  and  Lower  Medoc. 
Later  it  spread  to  central  France,  and  was  described  by  Pictet  in  1805 
and  by  Gohier  in  180H,  both  of  whom  declared  it  to  be  a  communicable 
disease.  It  was  likewise  observed  about  this  time  in  Piedmont,  Italy, 
and  spread  into  Germany  about  1815  as  a  result  of  the  introduction  of 
French  Merinos.  Not  only  has  it  appeared  in  epizootic  form  in  con- 
tinental Europe,  but  it  has  also  spread  through  Great  Britain,  Aus- 
tralia, and  the  United  States,  where  it  was  not  infrequently  observed 
during  the  past  century. 

The  date  of  its  first  appearance  on  American  soil  is  unknown.  The 
statement  has  frequently  been  made  that  the  disease  was  brought  to 
American  shores  by  the  colonists  through  importations  of  Spanish 
Merinos,  and  this  statement  seems  to  have  been  accepted  by  many 
writers  without  question  or  discussion.  The  first  importation  of  Span- 
ish Merinos  for  breeding  purposes  is  reported  to  have  been  made  in 
the  year  1808,  but  the  disease  had  become  well  established  in  this  coun- 
try prior  to  that  time.  Another  reason  for  considering  sheep  from 
Spain  very  improbable  as  originators  of  the  disease  upon  American 
soil  is  the  fact  that  the  sheep  of  Spain  have  been  remarkably  free  from 
foot-rot.  It  is  even  asserted  that  it  has  never  been  seen  on  the  dry 
table-lands  which  constitute  the  pastures  of  the  entire  region  south  of 
the  P3"renees.  Spanish  Merinos  may  have  introduced  the  disease 
here,  but  it  is  very  probable  that  they  were  fii-st  shipped  from  Spain 
to  some  other  country,  and  thence,  after  a  longer  or  shorter  stay  in 
their  new  home,  reshipped,  together  with  an  infection  of  foot-rot,  to 
America.  It  has  been  historically  stated  that  the  first  settlers  who 
attempted  to  establish  flocks  of  sheep  upon  the  prairie  farms  of  Ohio, 
Indiana,  and  Illinois  met  with  most  disheartening  experiences,  which 
were  in  a  measure  due  to  the  spread  of  foot-rot.  In  the  year  1797  an 
agricultural  settlement  was  made  in  Illinois  by  farmers  from  the  East- 
ern colonies,  who  brought  with  them  flocks  and  herds  of  the  sheep 
and  cattle  common  to  the  section  of  country'  whence  they  came.  Dur- 
ing the  decade  following  many  new  homes  were  established  in  the 
prairie  regions,  and  a  number  of  the  new  settlers  brought  with  them 
foundation  stock  with  the  intention  of  growing  large  flocks  of  sheep, 


8  BUREAU    OB^    ANIMAL    INDUSTRY, 

but  wolves  and  panthers  proved  to  be  verj^  destructive,  and  liver  dis- 
ease and  foot-root  also  hindered  the  establishment  of  large  bands,  until 
finally  the  pioneers  were  forced  to  be  content  with  small  flocks  that 
could  be  constantly  housed,  guarded,  and  given  careful  attention. 

The  farmers  of  Maryland  and  Virginia  were  taking  an  increasing 
interest  at  this  time  in  improved  sheep.  They  had  man}-  discouraging 
conditions  to  contend  with,  and,  although  it  is  possible  that  foot-rot 
was  not  known  among  their  flocks  at  this  time,  it  is  certain  that  much 
trouble  was  caused  by  the  appearance  of  "diseases,  dogs,  and  wolves," 
and  that  contagious  foot-rot  made  itself  known  and  feared  as  earh"  as 
1832  in  these  States, 

Owing  to  the  imperfect  knowledge  at  that  time  of  matters  pertain- 
ing to  bacterial  diseases,  the  sheep  owners  struggled  against  the  spread 
of  foot-rot  in  their  flocks  somewhat  unsuccessfully,  and  it  often 
required  constant  watchfulness  and  persistent  treatment  for  three  or 
four  years  to  eradicate  the  disease  after  it  had  become  thoroughly 
established  upon  the  premises  of  the  sheep  grower. 

Later  than  this,  in  the  late  "fifties"  and  early  "sixties,"  there  was 
a  marked  revival  of  interest  in  sheep  raising  throughout  the  Middle 
West,  and  at  this  time  many  who  had  previously  devoted  their  energies 
exclusively  to  grain  or  to  cattle  and  hogs  concluded  to  change  over  to 
sheep,  and  the  resulting  trafiic  in  these  animals  caused  them  to  be 
moved  about  over  the  country  roads  and  into  new  sections  of  the  agri- 
cultural regions  in  numbers  never  before  equaled.  In  several  instances 
these  traveling  flocks  carried  foot-rot  with  them  and  infected  the  flocks 
with  which  they  came  in  contact  along  their  routes.  The  States  of 
Ohio,  Michigan  (southern),  Illinois,  and  Iowa  were  most  seriously 
infected,  and  in  all  of  them  the  disease  secured  such  firm  foothold  that 
several  years  of  strenuous  combat  were  necessary  before  it  was  even 
partially  subdued.  It  was  during  this  period  that  a  sheep  raiser  of 
long  practical  experience,  in  writing  from  his  home  State  (Ohio)  made 
the  statement  that  farmerstin  his  part  of  the  country  had  in  times  past 
been  seriously  troubled  by  the  appearance  of  stubborn  outbreaks  of 
foot-rot  among  their  flocks  of  sheep.  In  no  case,  however,  had  he 
been  able  to  discover  the  spontaneous  appearance  of  the  disease,  but 
with  a  little  persistent  inquiry  it  had  been  an  easy  task  to  trace  the 
origin  of  each  outbreak  to  the  careless  handling  of  diseased  sheep 
brought  from  other  localities.  Since  that  time  the  disease  has  appeared 
f  requentl}^,  but  its  spread  has  never  assumed  such  alarming  propor- 
tions, and,  owing  to  a  better  understanding  of  the  disease,  it  has  been 
more  successfully  controlled. 

The  change  from  former  methods  of  transportation  has  much  to  do 
with  the  prevention  of  such  widel}'  spread  outbreaks  as  the  one  just 
recorded.  Instead  of  driving  large  flocks  on  foot  over  many  miles  of 
highwa}^,  they  are  now  conveyed  by  rail  in  .such  a  manner  that  the 


FOOT-BOT    OF    SHEEP.  V 

possibility  of  transmitting  the  contagion  to  health}'  flocks  along  the 
route  is  avoided,  except  at  the  railway  stock  yards,  where  unloading 
is  necessary.  At  the  more  important  of  these  stock  yards  Federal 
inspectors  are  stationed,  who  are  very  careful  to  prevent,  so  far  as 
possible,  the  infection  of  health}'  flocks  while  in  transit.  The  disease 
is  by  no  means  eradicated  from  the  United  States,  however,  and  it 
occurs  at  irregular  intervals  in  certain  localities  with  as  great  viru- 
lence as  it  has  ever  shown,  and  it  is  only  because  of  a  more  complete 
knowledge  of  its  characteristics  that  its  spread  is  prevented  from 
becoming  more  general.  • 

SYMITOMS   AND   LESIONS. 

The  first  evidence  of  an  attack  of  foot-rot  to  attract  the  attention  of 
the  shepherd  is  a  slight  lameness,  which  rapidly  becomes  more  marked. 
Previous  to  this,  however,  there  has  appeared  a  moist  area  just  above 
the  horny  part  of  the  cleft  of  the  foot,  and  this  has  gradually  reddened 
and  assumed  a  feverish,  inflamed  appearance.  It  may  first  become 
visible  either  at  the  front  or  back  part  of  the  cleft,  but  usuallv  the 
erosions  make  their  first  appearance  at  the  heel.  The  inflammation 
rapidly  penetrates  beneath  the  horny  tissue,  while  from  the  ulcerous 
opening  there  exudes  a  thin,  purulent  fluid.  The  lameness  has  increased 
and  the  region  of  the  foot  above  the  hoof  is  becoming  swollen  and  warm 
to  the  touch.  The  exudate  from  the  erosions  contains  pus  cells,  bits 
of  destroyed  tissues  of  the  foot,  and  bacteria.  It  possesses  an  odor, 
pungent  and  disagreeable,  but  at  the  same  time  ver}-  characteristic. 
The  experienced  sheep  man  is  frequently  able  to  detect  the  presiMice 
of  the  disease  among  a  flock  of  sheep,  e\'en  though  it  be  while  making 
a  casual  visit  to  a  strange  flock,  simply  by  means  of  the  diagnostic*  and 
unmistakable  odor  which  arises  from  the  affected  feet.  This  odor  is  so 
pathognomonic  of  the  disease  that  it  would  reveal  the  presence  of 
affected  sheep  to  one  familiar  with  the  character  of  the  infection,  even 
before  noticing  the  animals. 

The  erosion  progresses,  if  no  treatment  is  applied,  and  there  is  rapid 
formation  of  fistulous  passages  beneath  the  horny  covering  of  the  foot, 
while  the  softer  tissues  of  the  interdigital  space  are  gradual Iv  Incom- 
ing degenerated  and  purulent.  The  invading  microorganisms  possess 
marked  burrowing  propensities,  and  the  result  of  their  invasion  is  that 
large  areas  of  the  hoof  become  loosened  from  the  sensitive  tissues  lying 
beneath. 

Should  the  loosened  horny  tissue  be  cut  away  it  will  be  seen  that  the 
undermining  process  has  been  advanced  b}'  the  microorganisms  until 
numerous  ulcerative  channels  have  been  formed  which  are  filled  with 
grayish  purulent  matter  and  that  the  encroachment  upon  the  healthy 
areas  is  persistently  and  constantly  being  extended.     Should  but  om^ 


10  BUEEAU  OF  ANIMAL  INDUSTRY. 

■of  the  claws  of  the  foot  be  primarily  affected,  the  disease  maj'  readily 
spread  to  the  other  by  means  of  passages  or  channels  eroded  beneath 
the  skin  of  the  interdigital  space. 

The  invasion  of  the  necrotic  process  may  continue  until  ligaments, 
tendons,  and  even  the  bones  are  attacked;  but  before  this  final  stage 
is  reached  nature  will  attempt  to  repair  the  damage,  and  for  this  pur- 
pose the  secretion  of  formative  elements  in  the  injured  part  is  greatly 
increased,  until  there  appears  a  peculiar  growth  composed  of  horny 
elements,  dense  epithelial  cells,  and  granulation  tissue.  These  unsuc- 
<'essful  attempts  at  renewed  development  of  tissue  are  termed  "fungoid 
growths,"  and  they  have  been  known  to  materially  hasten  the  shedding 


Fig.  1. — Hoof  showing  effects  of  chronic  foot-rot. 

of  the  horny  covering  of  the  foot  by  their  persistent  enlargement 
within  the  ulcerous  channels  cut  by  the  advancing  infective  elements. 
The  hoof  of  a  sheep  suffering  from  a  chronic  case  of  foot-rot  grows 
out  rapidly  and  becomes  very  hard.  It  will  often  be  found  with  the 
toes  so  thickened  and  lengthened  that  the  front  part  of  the  foot  is 
raised  above  its  natural  incline  and  the  tendons  at  the  heel  are  sub- 
jected to  additional  strain,  all  of  which  tends  to  increase  the  lameness 
and  the  awkwardness  in  gait  of  the  victim.  These  thickened  and 
elongated  toes  will  frequently  be  seen  to  have  attained  an  added  length 
of  3  or  even  4  inches,  and  theycurluplike  sled  runners,  greatly  inter- 
fering with  the  progression  of  the  animal.     (See  Fig.  1.) 


FOOT-ROT    OF    SHEEP.  11 

The  sheep  finds  the  act  of  walking  so  painful  when  the  disease  has 
become  thoroughly  established  that  it  remains  quietly  lying  in  some 
.secluded  corner  or,  if  diseased  in  the  fore  feet  only,  crawls  around  on 
its  knees  in  its  efforts  to  keep  with  the  remainder  of  the  flock  or  to 
get  within  reach  of  its  food.  Its  temperature  rises  until  there  is  evi- 
dence of  considerable  fever.  The  appetite  is  seriously  impaired  and 
the  patient  rapidly  loses  condition  and  weight. 

During  warm  weather  there  is  great  danger  of  an  attack  by  mag- 
gots as  soon  as  the  lesions  are  discharging  freely,  and  unless  these 
are  quickly  removed  they  will  appear  in  such  numbers  as  rapidly  to 
bring  the  course  of  the  disease  to  a  fatal  ending.  They  not  only 
invade  the  affected  feet,  but  will  also  locate  at  any  point  of  the  bod\' 
at  which  the  wool  has  become  sufficienth'  contaminated  by  the  puru- 
lent discharge  from  the  ulcerous  tmcts  to  afford  them  a  suitable  moist- 
ened feeding  place.  The  wool  on  the  sides  of  the  body  is  frequently 
more  or  less  soiled  from  contact  with  the  diseased  feet  while  the  ani- 
mal is  lying  down,  and  it  is  in  such  areas  that  the  fly  deposits  the  eggs 
that  hatch  into  destructive  larvae.  As  soon  as  the  maggots  are  hatched 
they  begin  to  burrow  into  the  tissues  upon  which  they  are  located  and 
they  quickl}'  perforate  the  skin  of  their  host,  thus  causing  complica- 
tions which  bring  its  suffering  to  a  close. 

It  having  been  found  that  the  bacillus  of  necrosis  is  the  cause  of 
foot-rot  in  reindeer  as  well  as  in  sheep,  the  following  description  by. 
Home  of  the  disease  in  the  reindeer  of  Scandinavia  is  here  given,  that 
the  reader  may  note  the  great  similarity  of  the  course  of  the  disease, 
as  well  as  the  macroscopic  lesions  produced  by  this  microorganism  in 
the  feet  of  these  two  species  of  animals: 

One's  attention  is  called  to  the  disease  by  the  fact  that  the  reindeer  becomes  lame, 
walks  with  difficulty,  and  remains  in  the  rear  of  the  herd.  As  the  disease  progresses 
the  affected  reindeer  becomes  unable  to  follow  the  rest  of  the  animals  in  their  wan- 
derings and  lies  down;  now  the  disease  advances  rapidly  and  the  animal  is  not  able 
to  seek  nourishment.  It  soon  becomes  emaciated  and  dies,  or  falls  a  prey  to  wolves 
or  other  wild  creatures.  The  disease  is  located  between  the  claws  of  the  hoof,  or  at 
the  lowest  joint  of  the  limb.  The  foot  swells  greatly,  so  that  it  resembles  a  club,  and 
hence  the  name  "club  disease."  The  diseased  foot  is  very  tender,  preventing  the 
animal  from  walking  upon  it.  After  a  while  the  hide  cracks  and  there  appears  in 
the  sore  a  peculiar  discharge.  The  pathological  picture  of  the  inflammatory  proce^ 
itself  and  the  transformation  of  the  web  into  a  dry,  yellowish  green  necrotic  mass, 
lead  to  the  opinion  that  it  must  have  been  a  process  similar  to  hoof  carbuncle  and  to 
the  other  diseases  brought  about  by  the  necrosis  bacillus. 

COURSE   AND   SUSCEITIBILITY. 

The  course  of  this  disease  is  slow  and  protracted,  usually  starting  with 
one  foot  and  subsequently  involving  one  or  more  of  the  others.  Dur- 
ing this  interval  it  would  probably  have  likewise  spread  to  the  feet  of 
other  sheep,  and  in  this  wa}'  the  disease  may  remain  for  several  months 


12  BUREAU    OF    ANIMAL    INDUSTRY. 

in  each  member  of  the  flock  and  for  eight  or  ten  months  in  the  flock 
itself.  Wlien  the  ulcerous  processes  have  become  advanced  and  aggra- 
vated, fever  develops,  the  appetite  is  lost,  and  the  animal  grows  so 
emaciated  that  death  intervenes.  In  some  cases  that  are  left  untreated 
recovery  may  follow  slowly,  but  there  is  usually  either  a  dense  fun- 
goid growth  between  the  claws,  a  stiffening  of  the  joints  of  the  ankle, 
or  a  long  fissured  and  misshapen  hoof.  When  treatment  is  properly 
applied  in  the  early  stages  of  the  disease,  it  is  usually  cured  within 
ten  days.  It  is  very  rare  for  death  to  occur  as  a  result  of  foot-rot, 
although  in  very  virulent  outbreaks  involving  3  or  4  feet  of  each  sheep 
the  affection  may  terminate  fatally  within  two  or  three  months. 

The  course  of  the  disease  is  also  dependent  upon  the  susceptibility 
of  the  affected  animal.  Thus,  it  is  a  well-accepted  fact  that  the  pure 
breeds  of  fine-wooled  sheep  are  especially  susceptible  to  foot-rot, 
although  the  pure  breeds  of  coarse-wooled  sheep  and  the  grades  of 
both  of  these  breeds  of  animals  are  by  no  means  exempt.  In  the  lat- 
ter animals,  however,  the  disease  runs  a  milder  course,  and  is  more 
amenable  to  treatment  than  in  the  case  of  the  fine-wooled  sheep.  Sex 
or  age  does  not  appear  to  have  any  important  influence  on  the  suscep- 
tibility of  the  animals,  as  the  disease  manifests  itself  quite  generally 
in  the  flock,  attacking  lambs,  yearlings,  and  aged  sheep  alike,  without 
regard  to  their  being  male  or  female. 

CONTAGION. 

Some  of  the  early  writers  seem  to  have  been  convinced  that  this 
disease  was  in  no  degree  contagious,  but  at  a  later  period  man}'  inves- 
tigators opposed  this  opinion  and  strongly  maintained  that  it  spread 
from  sheep  to  sheep  by  means  of  some  contaminating  agent  which 
exuded  from  the  erosions  upon  the  affected  feet. 

In  opposition  to  these  statements  many  veterinarj^  writers  were 
positive  in  their  declarations  that  the  disease  was  never  caused 
otherwise  than  by  pasturing  on  low,  swampy  lands,  or  as  a  result 
of  overgrown  toes,  or  by  other  conditions  due  to  faulty  care  and 
surroundings.  This  view  is  concisely  presented  in  the  following 
statement  by  a  writer  of  prominence: 

By  nature  not  unlike  the  goat  it  (the  sheep)  frequents  the  summits  of  the  lofty 
mountains,  where  its  hoofs,  altogether  analogous  to  those  of  the  horse,  are  expose<l 
to  much  wear  and  tear.  When  from  these  alpine  regions  we  transfer  the  sheep  into 
our  grassy  lawns,  our  moorish  lands,  or  sandy  soils,  this  wearing  away  of  the  crust  is 
put  an  end  to;  it  grows  too  long  and  proves  a  great  incumbrance.  In  this  state  it  is 
necessarily  exposed  to  many  injuries,  among  others  from  the  long  grass  of  the  pas- 
tures, and  itself  necessarily  injures  th«  soft  parts  beneath;  and  hence  lameness, 
inflammation,  suppuration,  to  the  extent  of  casting  the  hoof,  are  the  consequences. 
The  circumstance  of  the  disease  occurring  epidemically  arises  from  the  whole  flock 
being  placed  in  precisely  similar  circumstances. 

The  above  paragraph  has  been  widely  quoted  and  seems  to  have 
formed  the  basis  of  a  long  list  of  arguments  in  favor  of  the  noncon- 


FOOT-ROT   OF    SHEEP.  13 

tagiousness  of  foot-rot.  But  while  the  majority  of  writers  seem  to 
have  denied  that  the  disease  possessed  any  contagious  properties, 
there  remained  a  very  livel}"  minority  who  entered  a  most  vigorous 
protest  against  this  view  of  its  character,  and  who  cited  instance  after 
instance  in  support  of  their  claim  that  it  was  strictly  of  a  contagious 
nature.  They  mentioned  cases  in  which  aflfected  sheep  had  been 
brought  from  a  distance  and  placed  in  flocks  that  had  been  sound  and 
healthy  for  years,  with  the  result  that  a  portion  of  the  flock  soon 
became  aflfected;  also  a  case  in  which  healthj'^  and  diseased  flocks  pas- 
tured in  adjoining  fields  without  any  transmission  of  the  trouble  until 
a  time  when  two  or  three  of  the  sound  animals  jumped  the  dividing 
fence  and  grazed  for  the  remainder  of  the  da}'  with  the  contaminated 
flock,  with  the  result  that  thej^  promptly  contracted  foot-rot^  These 
writers  recorded  the  infection  of  sound  flocks  as  the  result  of  their 
having  been  driven  over  roads  which  diseased  sheep  had  traversed 
but  a  short  time  previously.  Reports  were  made  of  test  lots  of  sheep 
that  were  pastured  for  months  on  swampy  and  muddy  lands  without 
spontaneous  development  of  foot- rot,  which  promptly  became  affected, 
however,  on  their  removal  from  these  pastures  when  inoculated  on  the 
skin  between  the  claws  of  their  feet  with  discharge  from  an  affected 
foot.  They  mentioned  several  attempts  at  experimental  inoculation 
with  bits  of  diseased  tissue,  or  with  some  of  the  moist  excretions  from 
an  affected  foot,  which  usually  favored  the  investigator  with  successful 
terminations. 

One  of  the  best  of  these  experiments  was  reported  by  Favre  in  1823. 
He  simply  moistened  the  skin  between  the  claws  of  32  healthy  sheep 
with  matter  obtained  from  diseased  feet,  with  the  result  that  21  of 
them  contracted  the  disease  in  consequence  of  this  slight  exposure. 

Another  convincing  argument  in  favor  of  the  dependence  of  foot- rot 
on  a  specific  cause  is  found  in  the  fact  that  j^oung  lambs  yeaned  by 
affected  ewes  have  been  known  to  show  unmistakable  symptoms  of  the 
disease  as  early  as  the  sixth  day  after  birth,  and,  as  this  has  occurred 
in  flocks  that  have  been  closely  stabled,  there  remains  no  possibility 
that  the  lameness  of  these  lambs  could  have  originated  in  swampy  or 
muddj'  pastures. 

Additional  evidence  of  the  contagious  nature  of  the  disease,  as  well 
as  an  example  of  one  of  the  ways  in  which  the  infection  may  be  placed 
where  it  will  do  great  harm  to  innocent  parties,  will  be  found  in  the 
following  account  of  an  outbreak  in  one  of  the  small  country  towns 
of  Vermont  several  years  ago.  A  ciirload  of  thin  sheep  were  shipped 
out  from  Boston  to  be  fattened  on  one  of  the  stock  farms  of  that 
vicinity,  with  the  intention  of  reshipping  to  the  Boston  market  when 
finished.  They  arrived  at  their  new  home  in  the  fall  of  the  year,  a 
season  in  which  there  is  always  great  activity  among  stock  owners  in 
preparation  for  the  winter.     Many  of  them  were  infected  with  foot- 


14  BUREAU    OF   ANIMAL   INDUSTRY. 

rot  at  the  time  of  their  purchase,  but,  in  spite  of  this  fact,  they  were 
unloaded  with  the  rest  of  the  flock,  and  all  were  driven  over  several 
miles  of  countr}^  highway  from  the  station  to  their  owner's  farm.  The 
result  of  this  journey  was  that  four  other  bunches  of  sheep  that  soon 
traversed  the  same  route  or  portions  of  it  became  affected  with  foot- 
rot  in  its  most  virulent  form.  The  owners  tried  every  form  of  treat- 
ment that  they  could  hear  of,  but  only  with  unsatisfactory  results,  and 
the  disease  was  not  wholly  eradicated  from  the  affected  district  until 
the  fourth  year  after  its  introduction. 

Writers  of  recent  years,  both  in  Great  Britain  and  Finance,  have 
become  more  and  more  willing  to  declare  that  the  disease  owes  its 
origin  and  perpetuation  to  a  specific  cause.  Many  German  writers 
still  have  the  disease  inextricably  confused  with  foot-and-mouth  dis- 
ease, an3  for  this  reason  their  literature  does  not  offer  the  assistance 
to  a  student  of  the  ailments  of  the  sheep  that  one  would  naturally 
expect  to  gain. 

Innumerable  instances  have  been  recorded  in  American  agricultural 
periodicals  which  indicate  very  clearly  that  foot-rot  of  sheep  is  an 
affection  which  is  in  no  respect  related  to  foot-and-mouth  disease,  and 
they  also  show  that  the  disease  possesses  some  contagious  principle 
whereby  it  maj-  be  readily  carried  from  flock  to  flock  or  from  a  dis- 
eased to  a  healthy  animal  on  the  same  premises. 

Among  the  first  experiments  made  by  this  Bureau,  preparatory  to 
the  publication  of  this  article,  were  some  for  the  purpose  of  investi- 
gating the  contagious  nature  of  the  disease.  It  may  be  of  interest  to 
mention  in  this  connection  that  the  material  with  which  our  experi- 
ments were  made  was  derived  from  five  individual  outbreaks  of  foot- 
rot  in  different  States  and  in  no  way  connected  one  with  another. 
The  first  case  investigated  came  from  a  flock  of  Merino  sheep  in  Ohio. 
The  material  obtained  to  confirm  these  first  results  was  secured  at  the 
Buffalo  stock  yards  from  the  feet  of  three  affected  Shropshire  sheep 
that  were  shipped  from  Michigan.  The  third  outbreak  was  observed 
at  Deerpark,  Md. ,  in  Rambouillet  Merinos,  which  had  been  imported 
into  this  country  only  five  weeks  before.  The  fourth  outbreak  inves- 
tigated was  in  a  flock  of  sheep  near  Martinsburg,  W.  Va.,  from  which 
a  grade  Shropshire  was  received  at  this  office,  while  the  last  material 
obtained  consisted  of  two  badly  affected  Merino  sheep  from  New 
York  State.  By  means  of  careful  tests  performed  with  the  purulent 
exudate  from  the  feet  lesions  of  these  animals  it  was  proved  that  foot- 
rot  could  be  produced  at  will  in  healthy  sheep,  not  only  by  spreading 
a  little  purulent  matter  from  a  diseased  foot  upon  the  shaven  inter- 
digital  skin  of  sound  feet,  but  quite  as  readily  when  bouillon  cultures 
inoculated  with  some  of  the  discharge  from  an  affected  foot  were 
applied  in  a  like  manner,  even  when  the  cultui'es  used  were  of  the 
third  generation  of  the  original  growth. 


FOOT-ROT   OF   SHEEP.  15 

.  It  appeared  from  these  experiments  that  the  disease  was  dependent 
upon  a  specific  or<?anism  for  its  existence,  and  that  this  organism 
could  be  readily  perpetuated  by  the  employment  of  the  usual  methods, 
of  bacteriological  culture. 

BACTERIOLOGY." 

All  early  attempts  to  recover  an  organism  from  an  affected  foot  that 
would  produce  the  disease  when  applied  to  the  foot  of  a  healthy  sheep 
'  proved  failures.  It  was  only  by  the  inoculation  of  rabbits  or  mice 
and  the  application  of  anaerobic  conditions  that  the  slender,  straight 
or  wavy  rods,  constantly  present  in  the  affected  feet,  could  be  isolated 
in  purity.  A  mixed  culture  obtained  by  inoculating  ordinary  nutrient 
bouillon  with  pus  from  a  diseased  foot  was  found  to  retain  its  virulent 
principle  for  at  least  a  month  and  a  half  and  to  the  third  generation^ 
This  culture  would  produce  the  disease  in  the  foot  of  a  healthy  sheep,, 
the  lesion  appearing  in  from  three  to  nine  days  after  its  application  to 
the  shaven  skin  in  the  cleft  of  the  foot.  First  a  moist  condition  of 
the  surface  of  the  skin  was  noticed,  followed  by  various  inflamed  spots,. 

Description  of  Plate  1. 

Fig.  1. — Bacillus  necrophorus  from  a  10-day-old  bouillon  culture  stained  with  Loef- 
fler's  methylene  blue. 

Fig.  2. — Ten-day-old  bouillon-agar  growth  of  this  bacillus  stained  with  Loeffler's 
methylene  blue. 

Fig.  3. — Cover-glass  preparation  showing  the  bacillus  of  necrosis  obtained  froni 
the  purulent  exudate  from  the  foot  of  sheep  No.  108  after  artificial  inoculation  with 
pus  from  a  case  of  foot  rot. 

Fig.  4. — Forty-eight-hour-old  bouillon  culture  showing  short  forms  of  BacUlu» 
necrophorus  obtained  by  inoculating  this  medium  with  the  material  represented  in 
figure  3. 

Fig.  5. — Cover-glass  preparation  made  from  the  pus  of  a  foot  affected  with  a  long^ 
standing  spontaneous  case  of  foot-rot  and  showing  the  presence  of  various  micro- 
organisms, including  Bacillus  necrophorus. 

Fig.  6. — Cover-glass  preparation  made  from  the  purulent  discharge  from  foot  of 
sheep  No.  88,  seven  days  after  the  application  of  a  pure  culture  of  the  necrosis  bacillus 
that  had  been  obtained  from  a  case  of  foot-rot. 

These  six  camera-lucida  drawings  were  made  at  the  base  of  the  stand  with  Zeiss 
No.  4  compensating  ocular  and  2  mm.  oil  immersion  objective. 

Descsription  of  Plate  2. 

Fig.  1. — Cover-glass  preparation  made  from  gelatin-agar  colony  obtained  from  the- 
liver  of  a  rabbit,  which  was  the  third  in  a  series  inoculated  from  the  foot  of  an 
infected  sheep.  Stained-  with  Loeffler's  alkaline  methylene  blue.  Camera-lucida 
drawing  made  with  2jeis8  No.  6  compensating  ocular  and  2  mm.  oil  immersion 
objective. 

Fig.  2. — Liver  of  rabbit  which  died  twelve  days  after  the  subcutaneous  inoculation 
of  Bacillus  necrophorus.    Stained  with  Loeffler's  alkaline  methylene  blue.     Caniera- 

«  A  more  detailed  «lescription  of  the  Bncilln,^  necrophorus  will  be  given  in  a  forth- 
coming publication  on  necrotic  stomatitis  (calf  diphtheria). 


16  BUREAU    OF    ANIMAL   INDUSTRY. 

lucida  drawing  made  with  Zeiss  4  mm.  objective  and  No.  6  compensating  ocular. 
Notice  the  invasion  of  the  normal  liver  structure  by  the  necrosis  bacilli  arranged 
Along  the  border  of  the  necrotic  focus. 

Description  of  Plate  3. 

Fig.  1. — Bouillon-agar  culture  (first  dilution)  of  Bacillus  necrophorus,  showing 
■24-hour  growth,  with  numerous  small  gas  bubbles,  but  the  colonies  have  not  devel- 
oped suflBciently  to  become  visible. 

Fig.  2. — Seven-day-old  bouillon-agar  culture  of  this  organism  of  the  fourth  dilu- 
tion. The  isolated  colonies  are  characteristic  in  that  their  grayish  centers  are  sur- 
rounded by  fuzzy  white  areas,  not  unlike  the  strands  of  loose,  fleecy  cotton. 

Fig.  3. — Single  colonies  of  the  necrosis  bacillus,  showing  this  filamentous  character 
of  their  growth  (enlarged  about  seven  diameters). 

which  rapidly  spread  and  coalesced.  Within  twenty-four  hours  of  the 
appearance  of  the  reddened  spots,  the  characteristic  burrowing  pro- 
pensities of  the  disease  were  in  full  evidence,  and  the  hoofs  were  soon 
undermined. 

Microscopical  examination  of  the  purulent  material  discharged  from 
the  open  sore  of  a  case  of  foot-rot  revealed  the  constant  presence  of 
various  microorganisms  (PI.  1,  fig.  5),  and  similar  examination  of 
the  mixed  bouillon  culture  that  had  proved  virulent  when  applied  to 
healthy  sheep  showed  that  some  of  these  bacteria  were  still  present 
in  the  latter  material.  Various  micrococci,  or  round  forms,  were 
present  in  both  samples.  Plump  bacilli  with  rounded  or  blunt  ends 
were  also  frequently  observed,  and  either  these  or  the  cocci  would 
readil}^  grow  under  common  methods  of  bacteriological  culture,  when 
isolated  in  pure  culture,  but  neither  of  them  would  show  lasting  harm- 
ful effects  when  placed  upon  the  foot  of  a  healthy  sheep.  That  such  a 
condition  of  mixed  infection  should  occur  must  appear  perfectly  natu- 
ral when  it  is  considered  that  the  affected  foot  is  exposed  to  the  manure 
and  filth  of  the  stable  and  to  the  mud  and  dirt  of  the  pasture;  and  it  is 
this  constant  presence  of  extraneous,  saprophytic  microorganisms  that 
is  a  factor  in  making  the  isolation  of  the  causative  agent  more  difficult. 
However,  there  appeared  in  each  sample  placed  under  the  microscope 
long,  straight  or  wavy  baccilli  which  were  found  to  compose  fully  one- 
Jialf  of  the  number  of  organisms  and  which  it  was* impossible  to  sepa- 
rate from  the  other  forms  by  an}'  of  our  methods  of  plating  (PI.  1). 
These  baccilli  were  not  of  sufficient  similarit}',  however,  to  lead  one 
to  suspect  that  they  were  related  organisms;  those  found  in  smears 
taken  directly  from  the  affected  foot  appearing  as  long  lines  or  threads, 
while  those  discovered  in  the  mixed  bouillon  culture  were  shorter,  more 
slender,  and  never  united  in  long  filaments,  usually  appearing  singly  or 
less  frequently  in  pairs  (PI.  1,  fig.  4).  Later  observations,  however, 
showed  these  to  be  but  differing  forms  of  the  same  organism,  the  dif- 
ferences being  due  to  the  conditions  surrounding  their  growth.  It 
was  found  by  repeated  tests  that  the  shorter  separate  forms  present  in 
the  mixed  bouillon  cultures  would  produce  the  long  filamentous  forms 
when  inoculated  upon  sheep  or  rabbits,  and,  conversely,  the  results 


BuuETiH  No.  63,  B.  A.  I. 


Plate  1. 


Fig.  I. 


Fig.  2. 


Fig.  3. 


Fig.  4. 


Fig.  5. 


Fig.  6. 


Bacillus  necrophorus  from  foot-rot  of  sheep. 

Haines,  del.  breukck  k  ussur  cs. pmilw^ 


1 


Bulletin  No.  63,  B.  A.  I. 


Plate  3. 


:Qai 


io 


'^i 


l^^ol 


SP^ 


wifii 


Fig.  3. 


Fig.  1. 


Fig.  2. 


Development  of  colonies  of  bacillus  necrophorus. 


BREUhtK  l»  KESSUR  CC  PMlLiil 


FOOT-KOT    OF    SHEEP.  17 

obtained  by  growing  these  long  filaments  in  mixed  culture  in  ordinary 
bouillon,  or  in  pure  culture  in  rabbit  bouillon,  gave  a  reappearance  of 
the  shorter  single  forms  so  uniformly  present  in  all  previous  examina- 
tions of  the  baccillus  when  derived  from  like  environment. 

The  isolation  of  this  bacillus  from  the  other  forms  of  bacteria  pres- 
ent offered  many  difficulties,  and  if  it  were  not  for  the  peculiar  sus- 
ceptibility of  the  rabbit  to  this  organism  it  would  be  a  task  closely 
bordering  on  the  impossible,  as  viewed  in  the  light  of  present  labora- 
tor}'  methods. 

Having  become  convinced  that  foot-rot  could  be'readily  transmitted 
from  diseased  to  healthy  sheep  b}^  the  use  of  mixed  cultures,  as  well  as 
by  pus  obtained  from  the  diseased  surface  and  applied  to  the  inter- 
digital  space  of  the  sound  foot,  it  became  desirable  to  obtain  directly 
from  the  sheep  a  culture  of  the  organism  which  is  immediately  respon- 
sible for  the  spread  of  the  inflammation  into  the  tissues  of  the  healthy 
animal.  To  accomplish  this  end  recourse  was  had  to  the  following 
plan:  A  health}^  foot  of  a  fresh  sheep  was  carefully  washed,  then 
sterilized  by  the  application  of  5  per  cent  carbolic  acid,  later  washed 
with  sterilized  water,  immediately  inoculated  from  the  foot  of  a  dis- 
eased sheep  which  was  occupying  a  box  stall  near  b}",  and  then  wrapped 
up  in  rolls  of  sterile  cotton,  over  which  a  close  linen  wrapper  was 
loosely  bound.  In  this  manner  much  of  the  contamination  from  con- 
tact with  the  stable  floor  was  avoided,  and  the  organisms  which  under 
these  coverings  could  multiply  and  cause  ulcerous  inflammation  must 
closely  represent  the  universal  agent  to  w^hich  the  spread  of  foot-rot  is 
due.  Plate  1,  fig.  3,  represents  the  appearance  of  smears  taken  during 
the  initial  stages  of  the  inflammatorj'  process  from  a  foot  thus  treated. 

Having  under  these  precautions  obtained  material  for  further  inoc- 
ulations, one  should  now  rely  upon  the  rabbit  or  white  mouse  for  the 
complete  isolation  of  the  causative  bacillus. 

The  subcutaneous  inoculation  of  a  rabbit  with  a  small  amount  of  the 
water}'  excreted  matter  from  a  diseased  sheep's  foot  will  result  in  the 
death  of  the  rabbit  in  four  to  seven  days.  A  second  or  pierhaps  a  third 
rabbit  must  now  be  used  before  one  may  hope  to  obtain  a  pure  culture 
of  this  bacillus.  The  first  rabbit  will,  however,  in  spite  of  the  con- 
taminating microorganisms  present  in  the  material  used  in  its  inocula- 
tion, show  very  characteristic  lesions  which  can  be  referred  to  the 
action  of  no  organism  other  than  the  bacillus  of  necrosis.  The  chief 
of  these  tvpical  changes  will  be  noted  at  the  point  of  inoculation, 
Avhere,  on  the  removal  of  the  skin,  will  be  found  an  irregular  area, 
about  H  to  2  inches  in  diameter,  lying  immediately  beneath  the  skin 
and  extending  down  for  a  greater  or  lesser  depth  into  the  muscular 
tissues.  This  area  presents  to  the  naked  eye  much  the  appearance  of  a 
flattened  mass  of  .soft,  fresh  putty,  and  to  the  nose  a  penetrating  odor 
as  of  gaseous  decomposing  flesh. 
7963— No.  63-04 2 


18  BUREAU    OF   ANIMAL   INDUSTRY. 

This  pulpy,  yellowish  white,  malodorous  mass  is  the  detritus  of 
muscular,  fatty,  membranous,  and  vascular  tissues  which  have  been 
attacked  and  destroyed  through  the  presence  and  by  the  effective  poi- 
sons of  the  bacillus  of  necrosis.  Extending  out  into  the  surrounding-^ 
tissues  for  about  half  an  inch  in  all  directions  will  be  found  a  zone  of 
inflammatory  tissue,  and  the  subcutaneous  tissues  of  the  abdominal 
region  will  appear  inflamed  and  edematous  through  the  gravitation  of 
inflammator}^  agents  from  the  local  lesion  caused  by  inoculation. 
Examination  of  the  soft  mass  found  in  the  necrosed  area  at  the  point 
of  inoculation,  shows  that  it  is  penetrated  in  every  direction  bj-  long, 
thread-like  bacilli,  and  a  small  scraping  of  this  material  used  for  the 
subcutaneous  inoculation  of  a  second  rabbit  serves  to  eliminate  a  large 
proportion  of  the  contaminating  microorganisms.  Because  of  the 
greater  purity  of  the  material  now  used,  the  inoculation  will  not  result 
fatally  until  a  period  varying  from  eight  to  fourteen  days,  and  in 
many  instances  it  will  be  found  that  this  length  of  time  has  proved 
sufficient  to  allow  the  circulation  to  take  up  a  few  of  the  bacilli  of 
necrosis  and  deposit  them  in  the  plexuses  of  lungs,  liver,  or  kidne3's, 
where  small  3'ellowish-white  spots  of  necrosis  will  result,  and  from 
these  spots  the  bacillus  of  necrosis  may  be  obtained  in  pure  culture. 

The  Bacillus  necrophorus  advances  in  its  destructive  invasion  of  the 
health}^  tissues  which  surround  focal  points  with  all  of  the  precision 
of  an  advancing  arm3\  Plate  2,  fig.  2,  illustrates  the  invasion  of  a 
healthy  section  of  liver  from  a  necrotic  focus,  and  at  the  same  time 
indicates  that  the  best  place  to  obtain  pure  cultures  of  the  micro- 
organism is  at  the  line  where  the  area  of  absolute  necrosis  is  sur- 
rounded by  a  zone  of  invasive  inflammation. 

From  rabbits  that  have  developed  secondary  lesions  of  necrosis  in 
the  visceral  organs  pure  cultures  of  the  necrophorus  bacillus  ma}'  now 
be  gained,  and  their  further  development  may  be  secured  by  the  utili- 
zation of  anaerobic  methods  of  culture. 

This  bacillus,  although  of  nearly  uniform  thickness,  0.75  to  1/^,  may 
grow  to  a  variety  of  lengths,  and  has  a  tendency  under  certain  condi- 
tions toward  the  formation  of  long,  slender,  slightly  wavy  threads. 
It  is  this  character  of  varying  from  small  coccoid  rods  to  long  fila- 
ments which  may  reach  a  length  of  lOOyw  that  denotes  its  pleomorphism. 

The  bacillus  being  an  anaerobe,  develops  an  active  growth  in  the 
absence  of  oxj^gen.  A  culture  medium  composed  of  1  part  of  blood 
serum,  1  part  gelatin  (10  per  cent),  and  2  parts  agar  (1.75  per  cent) 
will  support  ready  growth  of  the  bacillus  along  the  line  of  the  stab 
below  the  surface  of  the  mixture.  Equally  good  results  in  obtain- 
ing cultures  may  be  reached  by  the  use  of  stiffened  fluid  media  as  will 
be  derived  from  relying  altogether  upon  firm,  solid  material.  One  of 
the  best,  because  simplest,  preparations  will  be  found  to  consist  of 


FOOT-ROT    OF   SHEEP.  19 

ordinary  bouillon  to  which  sufficient  melted  agar  has  been  added  to 
afford  the  mixture,  when  cooled,  the  consistency  of  soft  jell3\ 

Tubes  supplied  with  Martin's  bouillon  or  neutralized  rabbit  ))ouillon 
and  inoculated  with  this  organism  produce  good  growths,  especially  at 
the  bottom  of  the  tubes,  when  placed  in  a  hydrogen  jar. 

Gelatin  agar  is  still  another  satisfactor3'  medium,  and  dev<'l<)i)s 
thrifty  colonies. 

It  has  been  found  necessary  to  rely  upon  dilution  b}'  transfer  from 
tube  to  tube  through  a  series  of  three  or  four  tubes  for  the  obtaining 
of  separate  colonies  of  the  bacillus,  as  our  attempts  at  plating  this 
organism  have  not  been  satisfactory.  It  has  been  noted  that  the 
reduction  of  the  numbers  of  colonies  in  tubes  of  a  certain  size  will 
always  be  accompanied  by  an  increase  in  the  dimension  of  each  colonj-. 
Plate  3,  fig.  1,  shows  a  24-hour  growth  of  the  bacillus  in  stiffened 
fluid  media  (bouillon  agar).  Numerous  small  gas  bubbles  will  be 
noted,  but  the  colonies  have  not  yet  developed  sufficient!}'  to  become 
visible.  These  will  appear  after  forty -eight  to  seventy-two  hours' 
growth  as  small,  yellowish-white  specks,  around  which  will  later 
develop  a  fuzzy,  white  area,  not  unlike  a  covering  of  loose,  fleecy 
cotton.  These  characteristic  colonies  are  better  shown  in  the  diluted 
culture  (PI.  3,  fig.  2),  seven  days  old. 

The  organism  not  only  produces  gas  during  the  period  of  its  growth 
in  artificial  culture  media,  but  the  same  characteristic  is  also  notice- 
able in  the  flesh  of  rabbits  that  have  succumbed  to  inoculation.  If  the 
carcass  of  the  rabbit  is  left  undisturbed  on  ice  for  eight  or  ten  hours 
after  death,  there  will  then  be  areas  present  surrounding  the  seat  of 
inoculation,  in  which  the  muscles  appear  darkened,  and  the  inter- 
fibrillar  spaces,  together  with  the  intermuscular  and  subcutaneous 
spaces,  will  contain  small  bubbles  of  gas,  and  show  edematous  infil- 
tration. 

Development  occurs  between  30°  and  40°  C,  the  tempemture  most 
acceptable  to  the  organism  being  35°  C.  It  does  not  stain  by  Gram's 
method,  but  takes  the  ordinar}'^  aniline  dyes,  often  presenting,  espe- 
cially the  longer  forms,  a  characteristic  beaded  appearance  (PI.  I, 
figs.  1  and  2). 

PATHOGENESIS. 

INOCULATION    OK   SHEEP." 

The  readiness  with  which  the  disease  will  spread  from  sheep  to  sheep 
when  the  flock  is  kept  under  suitable  conditions  for  such  spreading 
has  been  recognized  for  many  years  by  sheep  owners.     In  addition  to 

"We  are  indebted  to  Pr.  E.  C.  Schroeder,  superintendent  of  Experiment  Station, 
Bureau  of  Animal  Industry,  for  the  inoculation  of  many  of  the  sheep  in  this  experi- 
ment and  for  the  clinical  notes  concerning  them. 


20  BUREAU    OF    ANIMAL   INDUSTRY. 

the  practical  demonstration  of  its  contagious  character,  wliich  has  been 
given  in  past  years  in  nearly  every  sheep-growing  State  in  the  Union, 
numerous  experiments  have  been  made  by  interested  investigators  in 
different  countries  for  the  purpose  of  determining  the  cause  of  the 
transmission  of  the  disease  from  one  sheep  to  another.  These  experi- 
ments have  been  so  comprehensive  (see  the  writings  of  Brown^"and 
Law*)  tliat  the  preliminary  tests  one  must  make  in  an  investigation  of 
the  character  here  recorded  are  necessarily  repetitions  of  work  that 
has  previously  been  done  by  others.  In  spite  of  this  fact  several  of 
the  experiments  commonly  made  by  students  of  foot-rot  have  been 
repeated  during  this  investigation,  and  the  record  of  some  of  the  suc- 
cessful inoculations  with  material  from  diseased  feet  will  be  given 
here  merely  as  a  substantiation  of  the  claim  that  the  disease  is  strictly 
contagious. 

Direct^  hy  jyus  from  affected  foot. — Two  sheep,  Nos.  40  and  63,  were 
inoculated  on  the  scarified  interdigital  skin  with  some  of  the  exuded 
matter  from  an  infected  foot,  and  developed  the  disease  in  typical 
form  in  seven  days  in  each  case.* 

Sheep  No.  313  was  inoculated  with  discharge  from  an  infected  foot 
on  the  shaven  surface  of  the  cleft  of  its  foot.  This  was  followed  by 
the  appearance  of  a  characteristic  inflammation  on  the  ninth  day,  and 
the  inflammation  gradually  developed  into  the  usual  course  of  ulcera- 
tion seen  in  this  disease. 

Sheep  No.  108  was  inoculated  upon  the  shaven  surface  of  the  skin 
of  the  foot  with  discharge  from  a  diseased  foot,  following  which  a 
protective  application  of  moist  sterile  cotton  and  a  linen  bandage  was 
applied.  A  characteristic  case  of  foot-rot  developed  on  the  fourth  day 
as  a  result.  It  seems  probable  that  the  earl}'  appearance  of  the  dis- 
ease in  this  instance  was  brought  about  by  the  partial  exclusion  of  air 
and  by  the  retention  of  more  or  less  moisture  upon  the  treated  surface, 
through  the  agency  of  the  cotton  and  bandage. 

Lamb  No.  94  is  of  special  interest,  having  been  born  in  an  infected 
stall  in  December,  1901,  and  having  continued  until  March  10,  1902, 
in  daily  contact  with  diseased  sheep  without  showing  the  slightest 
evidence  of  lameness.  During  this  period  of  exposure  the  stall  in 
which  the  animals  were  confined  was  kept  dry  and  clean.  Had  mud 
and  moisture  been  present  for  the  animals  to  walk  about  in,  in  com- 
mon, the  result  wouid  doubtless  have  been  different.  This  test  was 
continued  for  seventj'-nine  days,  at  the  end  of  which  time  it  was  seen 
that  the  healthy  lamb  had  received  no  degree  of  infection,  although  the 
disease  had  slowly  continued  to  advance  in  the  feet  of  its  diseased  com- 
panions until  the  affected  members  had  become  deeply  eroded.    Follow- 

«The  figure  references  are  to  bibliography  at  end  of  bulletin. 

^In  many  cases  where  foot-rot  was  produced  by  inoculation  antiseptic  treatment 
was  applied  and  a  cure  effected  as  soon  as  the  disease  had  l^ecome  characteristic. 


FOOT- ROT    OF    SHEEP.  21 

ing  this  preliminaiy  test,  the  himb  was  directly  inoculated  on  March 
10  by  the  application  of  material  taken  from  a  diseased  foot  to  both  of 
its  feet  on  the  right  side.  The  interdigitsil  spaces  of  both  feet  were 
scraped  until  the  surface  l)ecarne  blood  tinged,  when  the  watery  exudate 
from  the  diseased  foot  of  sheep  No.  62  was  smeared  over  the  scraped 
surfaces.  There  appeared  on  })oth  of  these  feet  in  fifteen  days  char- 
acteristic lesions  of  foot-rot,  while  the  left  hind  foot  also  developed 
this  disease  from  natural  infection,  although  the  lamb  had  previously 
withstood  the  danger  incident  to  living  in  daily  contact  with  diseased 
sheep.  It  may  be  stated  in  this  connection  that  other  negative  results 
were  also  met  with  by  exposing  healthy  to  diseased  sheep,  but  although 
seven  such  experiments  did  not  produce  the  disease  these  can  in  no 
way  offset  the  positive  results  obtained,  considering  that  the  exposure 
pens  were  always  clean  and  dry  and  unlike  the  natural  conditions 
under  which  sheep  are  usually  kept. 

Indirect^  hy  cultures. — A  review  of  experiments  made  with  pure 
cultures  of  the  bacillus  of  necrosis  will  serve  to  show  the  part  which 
this  organism  is  capable  of  taking  in  the  development  of  foot-rot  in 
sheep. 

A  pure  culture  of  the  bacillus  was  obtained  from  the  liver  of  a  rab- 
bit, which  was  the  third  in  a  series  inoculated  from  the  foot  of  an 
infected  sheep.  This  pure  culture  was  then  applied  to  the  scraped 
surface  of  a  healthy  foot  of  sheep  No.  87.  The  surface  upon  which 
the  culture  was  placed  began  to  show  inflammation  on  the  tenth  day, 
appearing  reddened  and  moistened,  and  exhibiting  the  presence  of 
considerable  heat.  For  ten  days  more  the  irritation  appeared  to  pro- 
gress, until  at  the  end  of  that  time  a  painful  ulcer,  coated  with  a 
grayish-white  exudate,  had  formed.  Spontaneous  healing  commenced 
at  this  period,  but  its  progress  was  slow,  and  microscopic  examination 
of  the  watery  exudation  from  the  ulcerous  opening  taken  nearly  two 
months  later  showed  that  many  of  the  long  filamentous  forms  of  the 
necrophorus  bacillus  were  still  present  in  it. 

Another  healthy  sheep,  No.  88,  was  inoculated  upon  the  scraped 
surface  of  its  foot  with  the  same  material  as  that  used  in  the  preceding 
case.  The  response  was  much  more  prompt  (four  days)  in  this  case,  and 
the  ulceration  penetrated  the  tissues  of  the  foot  for  al)out  the  same 
depth,  while  the  final  healing,  which  occurred  by  scab  formation, 
required  about  the  same  length  of  time  for  \Xs  establishment. 

A  third  sheep,  No.  89,  to  which  the  l)acillus  was  applied  in  a  pure 
state,  showed  inflammation  of  the  foot  in  a  few  days  and  by  the  eighth 
day  was  sore  and  lame  as  a  result.  The  erosion  penetrated  beneath 
the  skin  of  the  heels,  constantly  excreting  foul-smelling  yellowish  pus. 
Spontaneous  healing  began  to  make  its  appearance  in  about  three 
weeks  after  the  inoculation,  and  rapidly  progressed  to  the  complete 
restoration  of  the  foot. 


22  BUREAU    OF    ANIMAL    INDUSTRY. 

A  fourth  test  of  a  similar  nature  gave  much  the  same  results, 
except  for  a  slight  loosening  of  the  hoof  from  a  portion  of  one  of  the 
toes. 

From  the  very  nature  of  the  conditions  surrounding  a  flock  of  sheep 
it  must  be  known  that  a  natural  infection  b3"  the  necrophoi'us  bacillus 
in  a  pure  state  is  an  utter  impossibilit}'.  There  must  of  necessitj^  be 
material  contamination  by  various  cocci  and  other  bacteria  from  the 
floor  of  the  sheep  pens,  or  from  nuiddy  yards  and  runs.  Many  of 
these  invading  forms  in  all  probability'  ofler  great  assistance  to  the 
necrophorus  bacillus  in  penetrating  normal  tissue  and  in  perpetuating 
and  extending  the  disease. 

The  character  and  appearance  of  the  material  discharged  from  a 
foot  inoculated  artificiall}'  with  a  pure  culture  of  the  necrophorus 
bacillus  indicate  that  there  is  a  slight  difference  between  the  disease 
when  produced  in  this  manner  and  the  natural  type.  The  same  red- 
ness of  the  surface  is  noted  and  the  same  tendenc}'  to  send  deepening 
processes  of  ulceration  and  degeneration  into  the  depths  of  the  foot 
ma}'  be  seen  in  both,  but  the  discharge  will  be  seen  to  consist  largelv  of 
soft  yellowish  pus  in  those  cases  in  which  the  foot  has  been  inoculated 
with  pure  culture  and  the  foot  afterwards  kept  dry  and  clean,  while 
in  the  natural  infection  under  ordinary  barnyard  conditions  and  in 
cases  produced  artifically  bj-  the  application  of  mixed  liouillon  cultures 
the  exudate  has  more  of  a  j^ellowish  gray  watery  appearance  mixed 
with  pus. 

There  is  no  noticeable  difference  in  the  odor  of  the  affected  feet 
whether  the  lesions  are  produced  naturall}'  or  artiffcially,  and  the 
same  disagreeable  stench  pervades  all  cultures  made  from  them,  espe- 
ciall}'  after  these  cultures  have  grown  for  forty -eight  hours  or  longer 
in  the  incubator;  and  it  is  a  remarkable  fact  that  the  same  odor  may 
be  detected  lingering  about  the  carcass  of  a  rabbit  which  has  suc- 
cumbed to  an  inoculation  with  necrosis  bacilli  in  all  cases,  whether  the 
bacteria  were  derived  from  cases  of  foot-rot  in  sheep  or  from  some 
other  source. 

The  following  experiments  were  made  with  tissue  containing  an 
abundance  of  necrosis  bacilli  and  with  mixed  bouillon  cultures  made 
from  the  pus  of  affected  feet. 

Sheep  No.  83  was  inoculated  under  the  skin  of  the  heel  with  mate- 
rial taken  from  the  center  of  a  necrotic  lesion  in  a  rabbit  that  died  as 
a  result  of  the  infection  of  the  necrosis  bacilli.  Here  the  attack  was 
prompt  and  serious.  The  aninial  was  unable  to  use  its  foot  by  the 
third  da}',  this  degree  of  lameness  lasting  for  fully  a  week.  The 
organism  penetrated  beneath  the  hoof  on  each  toe,  causing  it  to  be 
separated  in  each  instance  from  the  tissues  beneath.  A  profuse  dis- 
charge was  constantl}^  exuding  from  the  point  of  inoculation,  in  which 


FOOT-ROT    OB'    SHEEP.  23 

the  long  threads  of  the  necrophorus  bacillus  could  constantly  be 
demonstrated. 

Sheep  No.  102  was  inoculated  on  the  foot  by  the  application  of  a 
mixed  bouillon  culture  that  had  been  taken  direct  from  a  diseased  foot 
and  grown  in  an  incubator  for  fort3'-eight  hours,  at  a  temperature  of 
35°  C.  Foot-rot  was  well  established  in  the  foot  b}'  the  sixth  day  fol- 
lowing, and  its  course  was  rapid  and  acute. 

Goat  No.  71  was  successfully  inoculated  b}'  having  the  skin  of  its 
interdigital  space  bared  by  the  clipping  oflf  of  the  hair  and  the  exposed 
surface  then  smeared  with  mixed  bouillon  culture  of  the  third  genera- 
tion. As  a  result  of  this  procedure  the  disease  made  itself  manifest 
on  the  ninth  daj^  and  followed  a  typical  course  through  the  various 
stages  of  inflammation,  spreading  ulceration  and  necrosis. 

Suheutaneous  inoculations. — In  order  to  test  the  action  of  the  bacillus 
of  necrosis  when  applied  to  sheep  upon  some  part  of  the  body  other 
than  the  foot,  a  strong,  healthy  sheep  was  inoculated  subcutaneously 
on  the  inner  surface  of  the  thigh  with  1  c.  c.  of  a  bouillon  culture  which 
contained  the  necrophorus  bacillus  in  pure  state. 

A  spreading  area  of  inflammation  resulted  from  this  inoculation, 
making  itself  apparent  upon  the  third  daj^  and  graduall}^  extending 
until  the  animal  became  feverish,  ofi:"  its  feed,  and  showed  considerable 
lameness.  In  the  center  of  this  inflamed  area  an  abscess  the  size  of  a 
hen's  ^%%  developed,  which  ruptured  spontaneously  after  a  few  days' 
duration,  discharging  a  quantity  of  foul-smelling,  yellowish  watery 
pus,  within  which  great  numbers  of  necrophorus  bacilli  were  swarm- 
ing. Recovery  was  rapid  after  the  rupture  of  the  abscess,  and  in 
fifteen  days  after  the  inoculation  all  soreness  had  gone  and  only  a  scar 
I'eniained. 

This  experiment  was  repeated  with  sheep  No.  13  b}-  inoculating  it 
under  the  skin  of  the  left  shoulder  with  2  c.  c.  of  a  bouillon  culture 
obtained  from  lamb  No.  94.  Six  days  later  a  hard  tumor  three-fourths 
of  an  inch  in  diameter  by  one-half  inch  high  had  developed  at  the  seat 
of  injection.  This  lesion  likewise  remained  localized  without  showing 
any  indication  toward  involving  the  deeper  structures,  and  recovery 
followed  in  nineteen  days. 

Feeding  experiments. — Two  sheep  were  selected  for  the  puipose  of 
feeding  cultures  of  the  necrosis  bacillus,  in  order  to  disprove  that  the 
organism  has  anj'^  predilection  for  the  feet  when  ingested  with  the  food. 
These  animals,  Nos.  15  and  84,  each  received  100  c.  c.  of  a  bouillon 
culture  mixed  with  mill  feed  on  three  successive  da3's.  These  sheep 
were  slaughtered  thirteen  months  and  four  months,  respectively,  after 
the  beginning  of  the  experiment,  but  the  postmortem  examination 
failed  to  reveal  any  indication  of  necrosis  in  any  of  the  tissues, 
although  the  livers  especially  were  subjected  to  careful  examination. 


24  BUREAU    OF    ANIMAL    INDUSTRY. 

Injection  of  jllt'pates.  —  In  the  midst  of  successful  inoculations  of 
healthy  sheep  with  artificial  cultures  of  the  organism  concerned  in  the 
production  of  foot-rot,  it  was  deemed  advisable  to  test  the  filtrate  of 
some  of  these  virulent  cultures  to  see  if  there  was  any  ultramicro- 
scopic  organism  to  which  the  disease  could  be  credited.  A  48-hour 
growth  of  a  mixed  bouillon  culture  that  had  been  inoculated  with  the 
pus  from  an  affected  foot  was  divided  into  two  parts,  one  of  which  was 
used  without  alteration,  while  from  the  other  a  filtrate  was  obtained 
by  the  use  of  a  Roux-Chamberland  filter.  The  two  fore  feet  of  a 
healthy  sheep  were  next  prepared  for  inoculation  by  scarifying  the 
intei"digital  spaces,  the  same  treatment  being  accoi'ded  to  each  of 
them,  and  the  application  was  at  once  made,  using  on  one  foot  the 
unaltered  mixed  bouillon  culture,  and  on  the  other  some  of  the  filtrate 
derived  from  it.  The  inoculation  with  the  culture  in  which  the 
bacteria  remained  soon  resulted  in  a  serious  case  of  eroding  foot- rot, 
while  the  foot  which  received  only  the  sterile  filtrate  quickly  healed. 
In  order  to  determine  if  the  products  of  the  necrophorus  bacillus 
were  in  any  way  concerned  in  the  production  of  these  lesions  a  similar 
experiment  was  tried.  For  this  purpose  a  rabbit  bouillon  culture 
of  the  necrophorus  bacillus  of  three  days'  growth  was  used  by  retain- 
ing a  small  portion  for  direct  inoculation,  while  the  remainder  of  the 
media  was  passed  through  the  Roux-Chamberland  filter.  When  the 
unfiltered  culture,  which  was  swarming  with  the  above  bacilli,  was 
applied  to  the  scraped  interdigital  space  of  a  foot  it  soon  began  to  pro- 
duce the  inflammation  and  lameness  which  characterize  the  initial  stages 
of  foot-rot,  while  the  foot  which  received  the  filtrate  after  similar 
treatment  remained  unaffected. 

INOCULATION    OF   RABBITS. 

Rabbits  are  the  most  susceptible  animals  to  the  inoculation  of  the 
Bacillus  necrophorus^  and,  as  Loeffler  has  stated,  they  also  afford  a 
ready  method  for  isolating  this  organism  from  contaminations.  A 
number  of  rabbits  were  inoculated  subcutaneousl}^,  both  with  the  puru- 
lent discharge  from  a  foot  affected  with  foot-rot,  as  well  as  with  pure 
cultures  of  the  Bacillus  necrophorus^  and  the  characteristic  yellowish 
white  area  of  muscular  necrosis  with  the  peculiar  penetrating  odor 
was  prominent  in  both  instances.  In  the  former  cases  the  animals 
frequently  died  on  the  fourth  or  fifth  day,  probably  as  a  result  of  the 
mixed  infection  present,  but  even  in  these  animals  the  coagulation 
necrosis  of  the  muscles  about  the  point  of  inoculation  and  their  trans- 
formation into  a  putty-like  consistency  was  always  noted.  When  pure 
cultures  were  used  a  rabbit  would  live  from  eight  to  fourteen  da3's 
when  injected  with  0.5  c.  c.  under  the  skin  of  the  back.  The  result- 
ing lesion  is  fully  described  on  page  19.  It  frequently  happens  when 
life  has  been  prolonged  ten  or  twelve  days  that  metastasis  occurs  from 


FOOT-ROT    OF   SHEEP.  25 

the  local  lesion,  in  which  cases  irregular  yellowish  areas  of  focal 
necrosis  are  observed  most  frequently  in  the  liver,  and  occasionally  in 
the  lungs  and  kidneys.  Microscopic  examination  of  the  tissues  taken 
from  the  affected  area  or  from  those  lesions  in  the  liver  or  lung  that 
had  developed  as  a  result  of  metastasis  shows  the  presence  of  typical 
necrosis  bacilli  in  great  numbers.  In  the  case  of  organic  lesions  these 
organisms  are  seen  to  be  arranged  along  the  border  of  the  area  of 
necrosis,  while  the  central  portion  is  amorphous  without  showing  the 
presence  of  any  bacilli.     (See  PI.  2,  fig.  2.) 

INOCULATION   OF   MICE. 

White  mice  may  be  used  in  obtaining  the  necrosis  bacillus  in  purity 
by  inoculating  three  or  four  successive!}'.  However,  their  suscepti- 
bility to  the  organisms  frequently  found  in  foot-rot  makes  them  less, 
valuable  than  rabbits  for  this  purpose.  The  results  obtained  by  the 
subcutaneous  inoculation  of  0.1  c.  c.  of  an  emulsion  prepared  from 
the  foot  of  a  sheep  suffering  with  foot-rot  and  of  0.1  c.  c.  of  a  bouil- 
lon culture  of  necrophorus  bacilli  are  practically  the  same  if  the  mou.se 
in  the  former  instance  docs  not  die  of  .some  intercurrent  disease  within 
three  or  four  days  following  the  injection.  The  usual  course  of  the 
disease  in  these  animals  ranges  from  five  to  eleven  days.  The  first 
indication  noticed  is  a  rapid  emaciation  of  the  mouse,  with  a  rough 
staring  coat  and  a  gradual  drying-up  appearance  of  the  animal.  On 
postmortem  examination  the  point  of  inoculation  was  found  surrounded 
by  the  usual  picture  of  coagulation  necrosis  involving  the  subcutane- 
ous and  muscular  tissues,  and  in  many  cases  involving  the  abdominal 
muscles.  The  internal  organs,  especiall}'  the  liver  and  lungs,  and  in 
one  instance  the  spleen,  showed  small  foci  of  caseation  in  which  necro- 
sis bacilli  were  readily  observed  on  microscopic  examination. 

INOCILATION   OK   GUINEA   PIGS. 

Guinea  pigs  were  inoculated  with  pure  cultures  of  the  necrophorus 
bacilli  both  by  the  subcutaneous  and  intraabdominal  methods,  but 
always  with  negative  results.  Six  animals  were  used  in  each  experi- 
ment and  doses  ranging  from  0.25  to  1  c.  c.  of  a  48-hour  bouillon  cul- 
ture injected  without  producing  an}'  untoward  effects. 

VIRULENCE   FOR   OTHER   ANIMALS. 

Among  the  many  conditions  in  which  the  bacillus  of  necrosis  has 
been  found  as  a  producer  of  disease,  Francke'  states  that  it  is  shown 
by  the  writings  of  Bang  that  this  bacillus  is  the  causative  agent  of  a 
troublesome  foot  disease  of  cattle  which,  commencing  as  a  phlegmon- 
ous inflammation  of  the  soft  parts  of  the  foot  close  to  the  horn  of  the 
hoof,  shows  a  tendency  toward  necrotic  degeneration. 

Through  the  results  obtained  by  Rang  after  careful  research,  Francke 
is  enabled  to  state  positively  that  all  of  the  necrotic  and  gangrenous 


26  BUREAU    OF   ANIMAL    INDUSTRY 

changes  found  in  this  affection  of  cattle  are  due  to  the  invasion  of  the 
bacillus  of  necrosis  following  some  injury  to  the  foot. 

He  also  quotes  Von  Imminger  as  authority  for  the  statement  that 
the  bacillus  of  necrosis  is  the  causative  agent  in  an  infectious  disease 
of  the  feet  of  cattle  which  he  had  studied.  Von  Imminger  reached 
the  conclusion  that  there  could  be  no  doubt  of  the  contagiousness  of 
the  disease,  and  from  the  nature  of  the  pathological  changes  alwaj's 
present  he  concluded  that  the  bacillus  of  necrosis  was  probably  the 
active  agent  in  promoting  the  spread  and  continuance  of  the  disease. 
He  appears,  however,  to  have  made  no  bacteriological  study  of  these 
cases. 

Through  Francke's  own  investigations  he  has  found  that  the  bacillus 
of  necrosis  is  verj^  widely  distributed  by  nature,  and  that  it  is  very 
actively  concerned,  either  alone  or  as  accessory  to  some  other  virulent 
organism,  in  the  development  of  a  number  of  spreading  diseases  among 
the  domestic  animals,  and  that  wherever  found,  its  presence  is  mani- 
fested by  an  erosive  local  destruction  of  tissue. 

In  cattle  and  horses  necrotic  areas  are  sometimes  present  in  lungs  or 
liver,  the  origin  of  which  is  plainly  shown  b}"  microscopic  examina- 
tion to  be  the  long  threadlike  bacillus  of  necrosis. 

Ernst,*  who  has  made  a  careful  study  of  the  bacillus  of  necrosis, 
states  that  Bang  was  the  first  to  recognize  the  multiplicity  of  ways  in 
which  the  pathogenicity  of  the  organism  is  shown.  He  described  it 
as  the  active  factor  in  the  production  of  several  diseases  which  are 
characterized  by  more  or  less  necrotic  destruction  of  tissue,  in  cattle, 
horses,  deer,  hogs,  sheep,  and  kangaroo. 

In  writing  of  malignant  foot-rot  in  cattle,  Hess"  maintains  that  this 
disease  is  identical  with  contagious  foot-rot  of  sheep.  In  studying  the 
disease  as  it  appears  in  cattle  he  has  found  that  it  is  caused  by  a  micro- 
organism first  described  by  Loeffler,  and  by  him  named  '"''  Baeilliis 
necrophorusy 

Nocard  and  Leclainche*  state  that  it  is  permissible  to  consider  that 
foot-rot  of  sheep  is  caused  by  the  bacillus  of  necrosis,  but  they,  like 
Hess,  fail  to  present  an}'  bacteriological  evidencefor  their  assertion. 

Horne^  has  reported  a  ver}-  interesting  outbreak  of  sore  feet  among 
the  reindeer  of  Norway  from  which  he  has  recovered  the  Bacillus 
necrophorus.     This  author  writes: 

It  is  emphasized  that  the  disease  is  contagious;  it  is  declared  to  be  highly  con- 
tagious. The  malady  appears  to  be  spread  by  healthy  animals  walking  in  the  steps 
of  diseased  ones,  where  they  catch  the  infective  principle  from  the  ground  in  small 
sores  or  cracks  in  the  skin. 

ECONOMIC   IMPORTANCE. 

Throughout  the  Middle  West,  where  packing  houses  are  located  in 
many  of  the  largest  cities,  the  sheep-feeding  industry  has  attained 


FOOT-ROT   OF   SHEEP. 


27 


large  proportions.  At  points  situated  within  easy  reach  of  the  more 
important  slaughtering  centers  there  have  been  stations  established 
for  the  purpose  of  finishing  off  those  sheep  and  lambs  that  have  been 
shipped  from  the  ranges  farther  west  before  they  had  reached  a  suffi- 
cient degree  of  fatness  to  admit  their  being  dressed  to  advantage.  The 
.stations  are  located  within  easy  reach  of  several  of  the  more  important 
stock  yards,  thus  enabling  the  owner  to  take  advantage  of  a  favorable 
turn  in  market  quotations,  or  to  supply  any  shortage  that  ma}'  occur 
in  the  receipts  of  a  particular  grade  of  sheep  at  the  yards  with  which 
lie  is  associated. 

There  are  several  of  these  places  with  a  capacity  of  over  50,000  sheep 
each,  and  one  near  Chicago  that  can  accommodate  80,000,  as  will  be 
seen  by  the  following  list  of  feeding  stations,  the  total  of  which  shows 
that  683,000  sheep  can  be  finished  for  market  at  one  time.  This  list 
does  not  include  the  vast  numbers  of  animals  that  are  fed  in  the  feed- 
ing stations  of  the  far  West  nor  those  in  bunches  of  500  to  3,000  by 
j)rivate  individuals  throughout  the  central  Northern  States. 

Partial  list  of  sheep-feeding  stations  in  the  United  States. 


Location. 


Orand  Island,  Nebr 

Norfolk,  Nebr 

Nickerson,  Kans... 

8t.  Marys,  Kans 

Hanover,  Kans 

Columbus,  Nebr  . .. 

Valley,  Nebr 

Fremont,  Nebr 

.Stockdale,  111 

I.afox,  111 

Montgomery,  111 ... 
Kirkland,  111 


Capacity. 


25,000 
25,000 
25,000 
25,000 
8,000 
25,000 
3.%0C0 
26,000 
60,000 
60,000 
80,000 
40,000 


Location. 


Piano,  111 

Specht,  111 

Rochelle,  111 

Milldale,  111 

Oswego,  111 

South  St.  Paul,  Minn 

St.  Anthony  Park.  Minn 

Brighton,  Minn 

Trevor,  Wis 


Capacity. 


25,000 
2.'>,000 
20,000 
15,000 
15,000 
40,000 
60,000 
25,000 
2.5,000 


Total 


68.%  000 


It  is  customary  to  keep  the  animals  closely  penned  during  the  period 
of  their  fattening  at  these  establishments;  in  fact,  they  are  sometimes 
restricted  to  rather  uncomfortably  narrow  quarters.  They  are  divided 
into  lots  of  200  to  600,  to  suit  the  convenience  of  the  feeder,  and  each 
lot  is  provided  with  a  separate  pen  in  which  they  remain  from  the  time 
of  their  arrival  until  sufficiently  finished  to  warrant  the  continuance  of 
their  journey  to  the  packing  house.  In  many  cases  their  grain  is  sup- 
plied to  them  through  "self-feeders,''  by  which  means  a  suppl}'  is  kept 
constantly  before  them.  Water  is  also  available  at  all  times,  and  the 
incentive  to  active  exercise  is  ver}-  slight,  even  if  the  pen  were  large 
enough  to  allow  unrestricted  movements.  Under  these  conditions  an 
outbreak  of  foot-rot  quickly  assumes  serious  proportions.  While  the 
disease  will  not  of  necessity  spread  from  one  pen  to  an  adjoining  one, 
there  are  several  cases  on  record  where  the  cont^igion  has  been  so 
thoroughly  disseminated  among  individual  pens  in  which  a  few  infected 
sheep  have  been  placed  that  only  a  small  number  of  its  inmates  escaped 
the  attack.     Inspectors  of  the  Bureau  of  Animal  Industry,   United 


28  BUKEAU    OF    ANIMAL    INDUSTRY. 

States  Department  of  Agriculture,  occasionally  find  an  affected  flock 
among  the  arrivals  of  sheep  at  the  various  railway  terminals  in  which 
the  feet  of  as  many  as  75  to  80  per  cent  are  diseased  to  a  greater  or 
lesser  extent.  These  bunches  of  sheep  have  no  doubt  been  run  together 
in  the  feeding  pens,  and  the  percentage  of  diseased  animals  gives  one  a 
very  good  idea  of  the  infectiveness  of  foot-rot  under  these  conditions. 

The  sheep  raiser  or  feeder  who  carries  on  bis  business  upon  a  modest 
scale  is  often  just  as  seriously  injured  by  an  outbreak  of  foot-rot  in 
his  flock  as  is  anyone.  His  sheep  run  at  will  over  a  large  portion  of 
his  farm,  and  it  soon  becomes  so  thoroughly  contaminated  by  the 
repeated  passage  of  diseased  feet  that  the  owner  not  only  becomes 
thoroughly  discouraged  by  the  repeated  failures  of  his  attempts  to 
eradicate  the  contagion  from  the  premises,  but  his  neighbors  begin  to 
look  on  him  with  suspicion,  and  in  certain  instances  have  become  so 
aroused  as  to  warn  the  unfortunate  man  against  entering  upon  or 
crossing  their  holdings  until  he  has  succeeded  in  stamping  out  the 
dreaded  plague. 

The  importer  or  breeder  of  choice  registered  sheep  is  frequently 
damaged  materially  by  the  appearance  of  this  disease  among  his  val- 
uable animals.  Foot-rot  occasionally  develops  in  sheep  soon  after 
importation  from  European  countries  in  spite  of  careful  examination  at 
the  time  of  purchase.  In  these  cases  it  is  probable  that  the  virus  had 
become  lodged  in  some  deep  fissure  under  the  horny  covering  of  the 
foot  during  some  previous  exposure,  and  that  it  had  remained  latent 
in  its  hiding  place  until  favoring  conditions  stimulated  its  growth. 
Whatever  the  manner  of  propagating  the  infecting  agent,  the  fact 
remains  that  foot-rot  frequently  manifests  itself  among  flocks  of 
blooded  sheep  while  on  shipboard  en  route  to  this  country,  and  condi- 
tions here  favoring  the  spread  of  the  infection  from  sheep  to  sheep,  it 
is  not  uncommon  for  the  animals  of  certain  pens  to  show  serious 
lameness  b}'  the  time  the  port  of  debarkation  is  reached.  Another 
place  in  which  the  owner  of  improved  sheep  becomes  exposed  to  more 
or  less  danger  of  infection  of  his  best  specimens  is  at  the  live-stock 
shows  of  the  countr}',  where  his  animals  are  exhibited  side  by  side 
with  sheep  from  widely  scattered  localities.  This  danger,  however, 
is  reduced  to  the  minimum  by  the  excellent  care  given  to  both  animals 
and  pens  while  the  exhibition  is  in  progress.  The  greatest  danger  is 
probably  met  when  the  animals  are  loaded  and  unloaded  over  a  chute 
at  the  railway  station,  which  is  used  by  all  of  the  exhibitors  in  common. 

The  raising  of  Angora  goats  is  also  becoming  an  industry  of  great 
economic  importance.  Their  value  as  producers  of  mohair,  of  fleece- 
bearing  skins,  and  of  meat,  together  with  their  efiiciency  as  eradica- 
tors  of  brush  and  weeds,  is  bringing  them  into  increasing  favor  with 
practical  American  people,  while  their  beautiful  silky  coats  and  gentle 
dispositions  make  them  ver}^  attractive  as  pets  for  those  who  seek  to 


FOOT-ROT   OF   SHEEP.  29 

derive  pleasure  rather  than  profit  from  them.  At  the  present  time 
large  sums  of  money  are  invested  in  these  animals,  and  individual  flocks 
numbering  thousands  of  animals  are  not  uncommon  in  some  localities. 
An  asso(;iation  of  breeders  has  b^en  formed  which  supports  a  registry 
book,-  and  live-stock  exhibitions  at  which  the  Angora  forms  a  promi- 
nent feature  are  sure  to  attract  general  interest. 

The  experiments  which  have  been  made  at  this  laboratory  prove 
that  Angora  goats  may  readily  be  inoculated  with  foot-rot  from  sheep, 
and  that  where  sheep  and  goats  are  allowed  to  pasture  together  they 
may  be  indiscriminately  attacked  by  an  invasion  of  this  disease. 

To  what  degree  the  prevalence  of  foot-rot  among  sheep  and  goats 
ill  this  country  exists  can  not  be  accurately  stated,  for  the  reason  that 
our  statistics  are  not  sufficiently  numerous  to  furnish  a  basis  for  a 
reasonable  estimate.  Occasional  outbreaks,  especially  the  highly  viru- 
lent ones,  are  reported,  and  in  these  cases  about  three-fourths  of  the 
Mock  become  affected.  Owing  to  the  slow,  protracted  course  of  the 
ilisease  and  the  length  of  time  required  for  the  affection  to  pass 
through  a  bunch  of  sheep,  the  losses  occurring  from  the  shrinkage  of 
flesh  in  market  sheep  and  from  the  diminution  of  the  supply  of  milk 
for  the  sucking  lambs  of  the  affected  ewes  reach  material  proportions. 
In  addition  to  these  direct  losses,  the  owner  of  an  infected  flock  of 
full-blooded  animals  is  subjected  to  discouraging  failures  in  his 
attempts  at  selling  off'  his  surphis  breeding  stock,  as  prospective  buy- 
ers are  naturally  reluctant  to  introduce  lame  animals  into  their  sheep- 
folds.  The  time  and  labor  spent  in  the  treatment  of  the  feet  of  an 
infected  flock  should  also  be  brought  forward  in  this  calculation  of 
monetary  loss. 

DIFFERENTIAL    DIAGNOSIS. 

There  are  })ut  few  pathological  conditions  of  the  feet  of  sheep  or 
goats  that  may  be  mistaken  for  contagious  foot-rot.  When  lameness 
first  makes  its  appearance  in  a  flock  there  may  be  some  hesitancv,  how- 
ever, in  determining  the  exact  nature  of  the  trouble.  Lameness  may 
be  primarily  caused  in  these  animals  by  wounds  of  the  feet,  b}-  puru- 
lent inflammation  of  the  interdigital  space  (so-called  noncontagious 
foot-rot),  ])}'  stoppage  of  the  orifice  of  the  biflex  canal,  by  suppurative 
<'ellulitis  (cutaneous  al)scesses),  or  by  foot-and-mouth  disease,  and  for 
u  time  the  lesions  produced  by  any  one  of  these  causes  may  offer  a 
very  confusing  resemblance  to  those  chanictcristic  of  the  invading 
.stage  of  foot- rot. 

WOfXDS   Of   THE    FEET. 

It  occasionally  happens  that  in  running  over  fields  or  roads  where 
.sliarp  stones  abound  that  sheep  or  goats  will  puncture  the  skin  of  the 
interdigital  space  by  forcing  one  of  the  sharp  edges  of  a  stone  ])etween 
the  claws  of  the  foot.    This  accident  is  not  of  frequent  occurrence. 


30  BUREAU    OF   ANIMAL    INDUSTRY. 

and  the  fever  and  lameness  thus  produced  seldom  last  for  more  than 
a  few  days. 

Another  source  of  injury  to  the  feet  is  seen  where  bushes  or  coarse 
weeds  have  been  cut  off  close  to  the  ground,  leaving  stiff,  dense, 
pointed  stubs  standing  erect,  offering  with  their  firm,  sharp  ends  an 
enduring  menace  to  the  feet  of  all  unwarj'^  passers.  Another  common 
cause  of  accidental  lesions  to  the  feet  of  sheep  is  met  in  or  around 
their  stables,  where  loose  boards,  with  the  projecting  points  of  nails 
sticking  upward  from  their  surfaces,  are  carelessly  left  for  the  flock 
to  run  over  while  passing  to  and  from  their  shelter. 

The  foot  should  be  cleansed  with  a  5  per  cent  carbolic-acid  solution 
when  it  has  been  subjected  to  an  injury  which  leaves  an  open  sore,  and 
in  cases  in  which  the  formation  of  pus  ensues,  this  should  be  liberated 
by  the  use  of  a  clean  knife  or  needle,  after  which  the  application  of 
poultice  supported  bj-  a  light  soft  bandage  will  be  found  very  bene- 
ficial. 

PURULENT    INFLAMMATION   OF   THE    INTERDIGITAL   SPACE    (fOULs). 

This  condition  is  one  that  is  frequentl}'^  met  in  sheep,  and  it  has 
often  been  mistakenly  called  foot-rot.  From  this  faulty  naming  has 
arisen  much  of  the  controvers}'^  over  the  question  of  the  contagious- 
ness of  foot-rot.  Parties  who  have  had  experience  only  with  purulent 
inflammation  of  the  foot,  and  who  have  looked  upon  it  as  foot-rot. 
have  very  reasonably  asserted  that  foot-rot  is  by  no  means  contagious, 
that  it  appears  sporadically,  may  attack  but  few  members  of  the  flock, 
jdelds  promptly  to  treatment,  and  nearly  always  makes  its  appearance 
among  sheep  during  their  pasturage  upon  low,  swampy  land.  If  the 
term  foot-rot  is  used  at  all  in  connection  with  purulent  inflammation 
of  the  feet,  it  should  be  qualified  by  calling  the  affection  benign  or 
noncontagious  foot-rot,  in  order  to  avoid  all  confusion  with  the  real 
or  contagious  form  of  the  disease.  This  purulent  inflammation  may 
result  from  pasturing  on  wet,  filthj^  grounds  or  on  low,  marshy  lands. 
An  irritation  of  the  cleft  of  the  foot  occurs  which  is  followed  by  fis- 
sures in  the  skin  and  a  softening  of  the  horn  resembling  foot-rot.  In 
rainy  weather  sheep  that  are  pasturing  upon  clay  soils  often  accumu- 
late irritating  masses  of  twigs,  stubble,  or  small,  sharp  pebbles  in  the 
interdigital  space  of  the  foot.  These  substances  become  thoroughly 
embedded  in  moistened  clay  and  this  mixture  is  gradually  molded  to 
the  form  of  the  space  between  the  claws  of  the  foot.  In  this  position 
it  will  remain  for  days  unless  removed  by  force,  and  it  ma}'  be  the 
cause  of  serious  inflammation,  suppuration,  and  lameness  so  long  as  it 
retains  its  position  in  this  sensitive  place.  Ever}'  step  of  the  animal 
causes  the  projecting  points  of  the  offending  material  to  cut  deeper 
and  deeper  into  the  adjoining  tissues  of  the  foot.  There  ensues  swell- 
ing above  the  coronet  and  the  Avhole  of  this  region  becomes  reddened 
and  feverish.     Cases  have  been  noted  where  marsh  grasses  with  their 


FOOT-ROT   OF   8HEEP.  31 

saw-like  edges  have  become  entangled  in  the  cleft  of  the  foot  and  have 
remained  in  position  long  enough  to  set  up  a  painful  irritation  by 
their  constant  friction.  Finall}',  on  examining  the  foot  of  a  lame 
sheep  one  may  discover  the  presence  of  none  of  these  pointed  objects, 
and  still  the  inflammation  is  intense.  This  condition  has  been  known 
to  follow  the  entrance  of  particles  of  sand  and  gravel  into  the  cuts, 
cracks,  or  injuries,  and  one  should  alwa3\s  bear  this  in  mind  while 
looking  for  a  cause  for  lameness,  and  carefully  remove  the  grit  or  dirt 
which  may  be  present.  Sometimes  the  horn,  having  grown  rapidly 
because  of  the  unusual  stimulation,  may  inclose  the  gravel  and  retain 
it  within  the  foot  as  a  constant  source  of  irritation. 

Unless  these  irritating  substances  have  remained  in  position  long 
enough  to  cause  suppuration,  the  onl}'^  treatment  required  is  their 
removal.  If  suppuration  has  become  established  the  antiseptic  treat- 
ment previously  recommended  for  wounds  of  the  foot  will  be  found  to 
give  admirable  results. 

STOPPAGE   OF   THE    BIFLEX    CANAL. 

Sheep  and  goats  are  provided  with  a  secretory  gland  called  the  inter- 
ungulate  or  biflex,  situated  among  the  tegumentarj'  tissues  of  the  leg 
just  above  the  separation  of  the  digits.  The  orfice  of  the  little  vessel 
that  leads  from  this  gland  may  be  plainly  seen  upon  spreading  the 
toes  apart.  The  secretion  of  the  interungulate  gland  is  of  an  oily 
nature  and  serves  as  a  lubricant  for  all  tissues  in  the  cleft  of  the  foot 
that  are  subjected  to  friction  during  the  progression  of  the  animal. 
In  the  healthy  normal  foot  the  functions  of  this  little  secretory  organ 
are  carried  on  unnoticed,  l)ut  it  occasionally  happens  that  mud,  sand, 
or  some  other  gritt}'  substfince  becomes  forced  up  into  the  biflex  canal 
and  lodges  there,  not  only  choking  up  the  excretory  passage  of  the 
gland  above,  but  also  causing  inflammation  of  the  walls  of  the  canal, 
which  may  develop  into  extensive  suppuration  and  serious  lameness. 

This  aflfection  may  be  distinguished  from  contagious  foot-rot  by  the 
fact  that  the  ulceration  does  not  tend  to  invade  the  tissues  beneath  the 
horny  covering  of  the  foot,  nor  does  it  assume  an  infectious  character. 

The  orifice  of  the  canal  should  be  opened  by  thorough  wasliing,  after 
which  it  may  be  dressed  with  a  poultice  held  in  place  by  the  appliia- 
tion  of  a  soft  bandage.  Should  the  suppuration  have  become  so  deeply 
seated  that  it  will  not  yield  to  washing  it  may  be  found  necessary  to 
lance  the  part  in  order  that  a  passage  may  be  provided  for  the  escajje 
of  the  imprisoned  pus.  A  knife  with  a  small  keen  blade  should  be 
used  in  this  operation,  and  it  should  be  carefull}'  cleaned  l)oth  before 
and  after  using.  Poultices  should  always  be  applied  to  feet  that  have 
required  surgical  relief,  and  the  bandages  ought  not  to  be  permanently 
removed  until  the  wound  has  healed  over,  superficially  at  least,  as  it 


532  BUREAU    OF    ANIMAL   INDUSTRY. 

^\i\\  give  valuable  assistance  to  the  healing  process  by  keeping  dirt 
from  entering  the  injured  areas. 

SUPPURATIVE   CELLULITIS  (cUTANEOUS   ABSCESSES). 

Stockmen  whose  cattle  and  sheep  are  obliged  to  pass  daily  through 
muddy  3  ards  or  pens,  especially  if  the  mud  is  so  deep  that  passage 
requires  laborious  wading,  sometimes  notice  the  eruption  of  sores, 
varying  in  size  from  the  diameter  of  a  millet  seed  to  that  of  a  silver  dol- 
lar, upon  the  lower  extremities  of  animals  subjected  to  such  conditions. 
These  sores  may  appear  just  above  the  coronet,  farther  up  in  the 
region  of  the  ankle,  or  still  higher  until  the  skin  near  the  knee  becomes 
the  seat  of  the  lesion. 

The  first  indication  of  the  trouble  will  be  an  erection  of  the  hair 
over  the  affected  area,  quickly  followed  by  swelling  of  the  part,  and 
accompanied  b}^  a  marked  rise  in  the  body  temperature  of  the  animal, 
loss  of  appetite,  sluggishness,  and  rapid  wasting  of  condition. 

As  the  disease  advances,  each  of  the  inflamed  areas  develops  a  typ- 
ical abscess,  containing  creamy  pus  with  a  very  offensive  odor.  At 
this  stage  it  is  sometimes  discovered  that  one  or  more  of  these  abscesses 
iave  become  established  beneath  the  coronary  band  or  even  beneath 
the  horny  wall  of  the  foot,  although  in  the  majority  of  cases  the 
lesions  are  all  confined  to  areas  above  the  foot,  where  the  leg  has  a 
thick  hairy  covering.  Should  these  find,  lodgment  in  the  tissues  of  the 
foot  the}'^  may  be  mistaken  at  first  for  indications  of  contagious  foot 
rot.  But  the  discovery  in  this  region  of  a  circumscribed  abscess  filled 
with  pus,  with  the  simultaneous  appearance  of  similar  abscesses 
T)eneath  the  skin  of  the  leg  will  at  once  prove  to  the  owner  of  the 
flock  that  the  trouble  is  an  outbreak  of  cutaneous  abscesses  and  not  an 
attack  of  contagious  foot- rot. 

Although  this  disease  j'ields  readily  when  proper  treatment  is 
applied  during  the  earlj'  part  of  its  development,  it  will  often  termi- 
nate fatally  if  neglected.  The  skin  of  the  lower  part  of  the  leg  is 
comparatively  thick  and  resistant,  and  in  consequence  the  abscesses 
seldom  open  spontaneously,  but,  spreading  to  the  adjoining  subcu- 
taneous tissues,  assume  an  eroding  character  which  permits  the 
absorption  of  their  products  by  the  blood  vessels,  and  general  septic- 
emia and  death  result.  Investigations  from  a  bacteriological  stand- 
point, especially  those  of  Moore  *  and  Voges  ®,  prove  the  constant 
presence  of  pyogenic  streptococci  in  the  abscesses  of  the  skin,  and  they 
are  undoubtedl}'  the  cause  of  the  affection. 

In  many  instances  it  has  been  found  that  the  removal  of  the  flock 
from  their  muddy  surroundings  to  dry,  clean  quarters  has  the  desired 
efl'ect  of  checking  the  spread  of  the  disease.  More  advanced  cases 
demand  that  the  abscesses  be  opened  surgically  and  thoroughly  cleaned 
with  an  antiseptic  solution,  after  which  rapid  healing  usuall}'^  follows. 


FOOT-ROT  OP  SHEEP.  33 


POOT-AND-MOUTH    DISEASE. 


This  country,  most  fortunately,  has  never  experienced  a  serious  out- 
break of  foot-and-mouth  disease  in  sections  in  which  the  sheep  industiy 
forms  an  important  factor  in  agricultural  activities.  It  is  one  of  the 
scourges  of  European  countries,  and  the  annual  reports  of  outbreaks 
of  contagious  diseases  in  these  lands  show  what  a  firm  footing  the  dis- 
ease has  gained  among  their  flocks  and  herds. 

Should  an  invasion  of  this  disease  ever  be  mistaken  for  foot-rot  in 
sheep,  the  illusion  will  not  be  one  of  long  duration.  The  eruptions 
which  appear  upon  the  feet  of  sheep  in  an  attack  of  foot-and-mouth 
disease  may,  during  the  invasive  period  of  the  outbreak,  bear  a  close 
resemblance  to  those  of  foot-rot,  but  they  are  more  superficial  in  their 
effect,  being  devoid  of  the  deep-seated,  erosive  passages  which  charac- 
terize the  foot-rot  lesion,  and  for  this  reason  they  are  far  more  tran- 
sient, disappearing  voluntarily  when  the  disease  has  run  its  course  in 
all  cases  in  which  the  attack  reaches  a  favorable  termination.  The 
lesions  of  foot-and-mouth  disease  are  more  plainly  to  be  seen,  the 
destructive  processes  frequently  extending  up  above  the  cleft  of  the 
foot  in  front  or  rear  into  plain  view  of  the  examiner.  In  uncomplicated 
cases  there  is  never  any  tendency  to  fungoid  growths,  and  the  struc- 
ture of  the  hoof  retains  its  normal  formation  and  does  not  become  soft 
or  crumbling,  as  it  frequently  does  after  an  attack  of  foot-rot.  The 
primary  attack  of  foot-and-mouth  disease  is  usually  evidenced  bv  the 
simultaneous  affection  of  at  least  three  of  the  feet  of  the  animal.  The 
infection  spreads  more  i*apidly  through  the  flock,  and  not  to  the  sheep 
alone,. but  to  the  cattle  and  hogs  which  are  permitted  to  mingle  with 
them.  In  addition  to  the  eruptions  on  the  feet  the  sheep  suffering 
from  foot-and-mouth  disease  will  occasionally  show  reddened  patches 
upon  the  membranes  of  mouth  and  lips  which  speedily  develop  into 
blisters  of  varying  sizes.  The  tongue  may  be  affected  in  the  same 
manner.  These  blisters  soon  rupture,  leaving  raw,  open  sores.  The 
teats  and  udders  of  affected  ewes  are  frequently  the  seat  of  like  erup- 
tions. The  temperature  of  the  animal  shows  marked  elevation  during 
the  invasion  of  the  trouble  (106'^  F.),  but  this  does  not  persist  after 
the  rupture  of  the  vesicles.  Lesions  of  the  mouth  are  not  so  constant 
in  sheep  as  they  are  in  members  of  the  bovine  family. 

A  number  of  European  writers  have  in  the  past  insisted  that  con- 
tagious foot- rot  of  sheep  does  not  exist  independently  of  foot-and-mouth 
disease;  but  the  very  fact  that  contagious  foot-rot  has  for  years  been 
more  or  less  prevalent  among  American  sheep  without  ever  having 
given  rise  to  foot-and-mouth  disease  among  the  cattle  and  hogs  of  the 
same  farms  offers  the  most  conclusive  evidence  that  the  diseases  are 
independent  one  from  the  other  and  that  they  have  their  origin  in  sep- 
arate, specific  organisms. 
7963— No.  63—04 3 


34  BUREAU    OF    ANIMAL    INDUSTRY. 

At  a  gathering  of  veterinarians  held  in  Saxon}'  an  address  was  given 
by  Martens'"  in  which  he  claimed,  in  direct  opposition  to  the  views 
held  by  a  majorit}'  of  his  colleagues,  that  malignant  foot-rot  of  sheep 
was  by  no  means  the  same  malady  as  foot-and-mouth  disease.  In  the 
course  of  his  remarks  he  said  that  the  malignant  foot-rot  of  sheep  has 
been  known  in  Europe  for  more  than  a  century  and  has  occurred  on 
many  sheep  farms  throughout  all  Germany,  where  it  has  proved  to  be 
a  plague  which  has  caused  great  damage.  In  some  of  the  flocks  it  had 
existed  for  many  years  in  spite  of  all  attempts  at  its  eradication. 

In  discussing  the  similarity  of  characteristics  which  exists  between 
foot-and-mouth  disease  of  sheep  and  contagious  foot-rot  in  the  same 
species  of  animal.  Martens*'  says  that  rapidit}'  of  spread  of  an  out- 
break among  the  animals  of  a  flock  is  not  alwa\'s  a  certain  indication 
that  the  disease  in  question  is  foot-and-mouth  disease,  as  he  has  seen 
over  30  per  cent  of  a  flock  attacked  with  foot-rot  in  the  course  of  a 
single  week  during  a  season  of  warm,  humid,  or  stormy  weatlier. 

PREVENTION. 

The  prevention  of  foot-rot,  a  matter  of  absorbing  interest  to  the 
sheep  owner,  may  be  successfully  attained  bj  means  of  careful 
management. 

When  purchases  of  sheep  are  to  be  added  to  a  healthy  flock  the 
buyer  can  not  exercise  too  great  caution  in  his  examination  of  the 
newcomers,  and  holding  them  for  a  few  daj's  in  isolated  quarters 
before  permitting  them  to  join  the  main  flock,  may  prove  to  be  time 
and  cfl'ort  well  spent.  Another  precaution  which  will  in  some  cases 
prove  beneficial  may  be  found  in  the  regular  examination  at  stated 
intervals  of  the  feet  of  each  member  of  the  flock,  and  the  removal  of 
all  excessive  growths  of  horn.  A  large  percentage  of  lameness  in  the 
horse  is  duo  to  an  ''  unbalanced  foot,"  and  the  first  step  in  treatment 
should  alwa3's  be  the  paring  of  the  hoof,  or  the  formation  of  the  shoe 
in  such  a  manner  that  the  foot  of  the  horse,  while  he  is  standing  at  ease, 
will  be  perfectly  level  in  its  relation  to  the  floor  surface  upon  which 
he  is  standing.  The  same  rule  holds  good  in  an  application  to  the 
ovine  race.  Overgrown  hoofs  should  he  so  trimmed  that  the  plantar, 
or  wearing,  surface  of  the  foot  will  present  a  natural  angle  to  the 
direction  of  the  bon}'  shaft  of  the  leg,  and  all  superfluous  length  of 
toe  should  be  removed.  Overgrown  toes  frequently  tend  to  forcibly 
spread  the  hoofs  apart,  the  tension  thus  produced  leading  in  many 
cases  to  strained  tendons  and  to  lessening  of  the  natural  resistance  of 
the  tissues  of  the  region  to  injury. 

A  great  amount  of  vital  energy  is  unnecessarily  expended  in  walking 
b\'^  a  sheep  with  overgrown  toes,  especially  if  the  animal  is  kept  in 
yards  or  pens  where  cornstalks  or  other  coarse  litter  are  allowed  to 


FOOT-ROT   OF    SHKEP.  35 

accumulate,  or  if  it  is  pa8tured  in  stubble  fields  or  where  the  grass  has 
become  long  and  tangled. 

The  heels  of  the  hoofs  seldom  require  any  cutting,  and  the  labor  of 
trimming  may  consequently  be  entirely  expended  upon  the  toe.  Soak- 
ing the  feet  for  a  time  will  be  found  to  soften  hoofs  that  are  at  first 
too  hard  to  yield  readily  to  the  knife.  It  will  bo  found  satisfactory, 
where  practicable,  to  select  a  time  for  trimming  the  hoofs  when  the 
flock  may  be  brought  up  to  the  pens  directly  from  an  excursion 
through  wet  grass.  The  early  morning  following  a  heavy  fall  of  dew 
is  frequently  selected  for  this  purpose,  oi*  the  work,  if  not  neglected 
too  long,  may  be  deferred  until  a  suitable  rainy  day. 

Should  the  infection  of  foot-rot  have  been  introduced  into  a  sheep 
yard  trimming  of  the  feet  will  not  prevent  the  spread  of  the  disease, 
except  as  it  indirectly  assists  nature  in  keeping  the  cleft  of  the  foot 
free  from  dirt,  and  the  wise  shepherd  will  not  relax  his  vigilance  at  the 
time  of  admitting  fresh  arrivals  upon  his  premises,  as  it  is  at  that  time 
that  he  may  most  easily  prevent  the  spread  of  this  disastrous  malady 
among  his  healthy  animals. 

Experience  has  shown  that  sound  sheep  may  be  safely  pastured  on 
land  that  has  previously  been  occupied  b\'  sheep  suffering  from  foot- 
rot,  provided  that  a  winter's  frosts  have  been  allowed  to  intervene. 
The  contagion  of  the  disease  seems  to  be  etfectivel}'  subdued  by  this 
means,  and  pastures  that  have  become  contaminated  one  season  ma}' 
be  considered  safe  for  their  customary  usage  during  the  following 
season.  The  sheepfold,  however,  must  be  carefully  disinfected  to 
prevent  the  recurrence  of  the  disease,  as  this  bacillus  will  retain  its 
virulence  under  suitable  conditions  in  or  around  stables  for  several 
3'ears.  The  walls,  racks,  and  troughs  should  be  sprinkled  with  a  solu- 
tion containing  1  pound  of  pure  carbolic  acid  to  5  gallons  of  water,  to 
which  enough  lime  has  been  added  to  make  the  spi'ayed  area  conspicu- 
ous. The  manure  and  4  inches  of  the  surface  soil  should  be  removed 
and  spread  on  a  field  that  is  to  be  tilled.  In  turning  sheep  on  gmss 
care  should  be  taken  to  avoid  low,  marshy,  or  boggy  lands,  and  to  keep 
them,  if  possible,  on  high,  dry  pastures. 

TREATMENT. 

One  of  the  first  steps  to  be  taken  in  the  treatment  of  a  flock  of  sheep 
affected  with  foot-rot  is  to  separate  all  that  are  in  any  degree  diseased 
from  those  that  are  healthy.  After  this  has  been  accomplished  much 
will  depend  upon  the  stage  which  the  disease  has  reached  among  the 
animals  of  the  flock  in  determining  upon  further  action.  Should  the 
disease  be  in  its  earliest  stage,  with  but  few  animals  affected,  it  will 
doubtless  be  found  suflScient  treatment  for  those  that  appear  sound 
to  pass  them  through  a  shallow  trough  containing  a  solution  composed 


36  BUREAU    OF    ANIMAL    INDUSTRY. 

of  1  pound  of  chloride  of  lime  to  each  12  quarts  of  water.  This  solu- 
tion should  have  a  depth  of  at  least  4  inches  in  the  trough,  and  the 
animals  should  be  made  to  pass  through  it  slowly,  allowing  time  for 
the  mixture  to  apply  itself  thoroughly  to  all  the  cracks  and  fissures  of 
the  feet.  Instead  of  the  mixture  of  chloride  of  lime,  a  solution  com- 
posed of  1  part  of  carbolic  acid  crystals  to  every  30  parts  of  water, 
or  1  pound  of  pure  carbolic  acid  to  4  gallons  of  water,  may  be  used  as 
a  foot  bath  for  the  sound  part  of  the  flock. 

The  trough  used  in  this  operation  may  be  of  wood,  tightly  con- 
structed, 20  inches  in  width,  and  a  foot  or  more  in  depth.  The  length 
should  be  proportioned  to  the  size  of  the  flock  to  be  treated.  For 
small  lots  that  are  accustomed  to  being  handled,  the  trough  need  not 
be  ov^er  6  feet  in  length.  In  such  cases,  however,  the  animals  should 
be  allowed  to  stand  for  a  moment  in  the  solution  before  passing  out. 
A  greater  length  of  trough  would  necessitate  the  preparation  of  a 
larger  amount  of  fluid,  and  consequently  would  entail  greater  expense. 
Where  a  large  number  of  sheep  is  to  be  treated  the  trough  should 
not  be  less  than  20  feet  in  length.  Hurdles  or  portable  racks  may  be 
so  arranged  by  the  sides  of  the  trough  and  along  the  pathway  lead- 
ing to  it  that  each  animal  may  be  obliged  to  pass  through  the  bath 
with  but  very  little  urging. 

After  this  treatment  has  been  applied  to  the  sound  part  of  the  flock, 
they  should  be  at  once  placed  in  fresh,  uncontaminated  quarters. 
Although  they  are  not  likely  to  show  any  evidences  of  the  disease  after 
being  treated  in  this  way,  the  owner  or  shepherd  should  not  neglect 
them,  but  should  closely  watch  for  any  signs  of  lameness,  and  when 
discovered  the  affected  animals  should  be  prompth^  removed  and  sub- 
jected to  more  careful  treatment.  In  case  the  flock  from  which  the 
healthy  sheep  were  separated  is  badly  diseased,  it  would  be  advisable 
to  have  the  sound  animals  pass  through  the  bath  as  described  above  on 
several  occasions.  This  may  be  done  ever}'^  second  day  until  three  or 
four  treatments  have  been  applied,  special  care  being  taken  in  the 
meantime  to  provide  fresh,  clean  quarters  for  the  animals,  completely 
separated  from  the  diseased  portion  of  the  flock. 

While  selecting  treatment  for  that  portion  of  the  flock  in  which  the 
disease  has  become  actually  established,  it  should  be  remembered  that 
the  principal  requisites  are  to  lay  bare  the  affected  surfaces  and  to 
destroy  the  infectious  matter  which  has  lodged  upon  them.  The 
remedy  which  will  accomplish  this  most  readily,  and  at  the  same  time 
without  giving  rise  to  harmful  secondary  conditions  is  evidently  the 
one  that  should  be  given  the  preference. 

The  bacteria  to  which  the  disease  is  due  yield  very  readily  to  the 
application  of  disinfectants,  and  the  trouble  which  so  many  sheep  men 
have  experienced  in  the  eradication  of  foot-rot  from  their  flocks  must 


FOOT-ROT    OF   SHEEP.  37 

have  been  due  to  a  failure  to  expose  properly  the  affected  surfaces  to 
the  action  of  the  applied  reined}'. 

During  the  present  course  of  experiments  many  of  the  feet  in  which 
disease  had  been  purposely  produced  have  been  healed  up  as  soon  as 
the  true  course  of  the  affection  had  become  evident,  so  as  to  avoid 
unnecessary  lameness;  and  in  these  cases  it  was  found  that  all 
advancement  of  the  disease  processes  promptly  stopped  upon  the 
application  of  a  5  per  cent  solution  of  carbolic  acid,  a  few  applications 
usually  proving  sufficient.  In  these'cases,  however,  it  must  be  admitted 
that  the  conditions  for  successfully  healing  the  lesions  were  far  more 
favorable  than  those  which  surround  the  average  diseased  flock  upon 
the  farm.  In  the  first  place,  the  erosions  had  not  extended  very  deeply 
into  the  foot,  and,  secondly,  the  animal  was  not  allowed  to  run  in  a 
muddy  yard,  but  was  kept  upon  a  dry  stable  floor.  The  instances 
.serve  to  prove,  however,  that  the  remedy  need  not  be  very  poisonous 
or  caustic  to  produce  the  desired  results,  and  to  emphasize  the  fact 
that  one  must  constantly  aim,  while  treating  foot-rot  in  sheep,  to 
expose  the  diseased  areas  to  the  action  of  the  disinfectant  used. 

Treatment  of  the  affected  animals  should  not  be  deferred,  as  more 
satisfactory  results  will  be  obtained  by  attacking  the  outbreak  as  soon 
as  discovered  than  can  be  expected  if  the  disease  is  permitted  to  spread 
among  the  flock  or  to  penetrate  deeper  into  the  tissues  of  the  affected 
feet.  This  is  accepted  as  a  very  practical  fact  by  the  English  shep- 
herds who  attend  shipments  of  thoroughbred  sheep  on  their  transat- 
lantic voA'age  to  this  country  for  breeding  purposes.  The  statement 
is  made  b}'"  them  that  none  but  negligent  or  inexperienced  shepherds 
will  ever  allow  foot-rot  to  spread  through  a  flock  of  which  the}'  are  in 
charge,  as  thorough  trimming  and  antiseptic  treatment  of  the  hoof  of 
the  first  animals  seen  to  be  lame  will  surely  save  the  balance  of  the 
.sheep  from  an  attack. 

The  treatment  alread}'  suggested  for  the  sound  portion  of  the  flock 
will  be  found  very  efficacious  for  earl}-  stages  of  the  disease,  but  after 
the  animal  has  become  more  seriously  affected  one  should  carefully 
examine  each  of  its  feet,  and,  if  necessar}',  pare  away  all  shredded  or 
loosened  portions  of  the  horny  tissue.  This  will  often  prove  to  be  a 
very  laborious  undertaking,  but  the  operator  should  persist  until  the 
loosened  horn  has  been  thorough!}'  removed  and  all  of  the  ulcerous 
fissures  have  been  exposed. 

The  foot  must  be  carefully  cleaned  and  every  portion  of  loosened 
and  detached  horn  cut  away,  as  the  horny  tissue  once  separated  from 
the  sensitive  parts  beneath  will  never  unite  with  them  again,  but  will 
remain  as  a  source  of  pain  and  inflammation  and  also  a  protection  for 
the  disease-producing  organisms  while  they  attack  and  destroy  the 
internal  structures.     Should  fungoid  granulations  be  met  they  should 


38  BUREAU  OF  ANIMAL  INDUSTRY. 

be  removed  with  a  knife  or  pair  of  curved  scissors.  All  clippings 
and  trimmings  that  are  removed  from  the  diseased  feet,  whether  com- 
posed of  bits  of  horn,  shreds  of  tissue,  or  fungoid  growths,  should  be 
carefulh'  gathered  up  and  burned  or  disinfected,  as  they  ma}'  serv^e  to 
spread  the  disease  further  if  left  where  passing  sheep  ma}'  come  in 
contact  with  them. 

If  this  work  has  been  thoroughl}'^  done,  standing  the  sheep  for  ten 
minutes  in  a  strong  solution  of  copper  sulphate  (blue  vitriol)  made  as 
warm  as  can  be  borne  b}^  the  hand,  will  in  most  cases  eflfect  a  cure. 
This  solution  may  be  prepared  by  dissolving  4  pounds  of  copper  sul- 
phate in  5  gallons  of  warm  water.  The  footbath  should  be  repeated 
if  necessary. 

An  attendant  should  remain  stationed  by  the  side  of  each  sheep 
whose  feet  are  badly  affected  to  prevent  the  animal  from  lying  down 
while  it  is  in  the  copper-sulphate  solution,  as  sheep  of  this  class, 
because  of  the  pain  produced  during  their  efforts  to  stand,  are  liable 
to  drop  to  their  knees  or  even  to  lie  down  in  the  trough  during  the 
application  of  the  treatment.  Soft  bandages  should  be  applied,  after 
the  sheep  are  removed  from  the  footbath,  to  all  feet  that  have  required 
deep  cutting,  not  only  for  the  purpose  of  protecting  the  sensitive 
tissue  from  becoming  bruised,  but  in  order  that  particles  of  dirt  ma}'^ 
be  kept  from  the  raw  surfaces,  and  that  nature  may  be  assisted  in 
the  formation  of  new  protective  coverings. 

It  sometimes  happens  that  the  disease  assumes  an  aggravated  form 
in  several  of  the  sheep,  involving  the  deeper  sensitive  tissues  and 
necessitating  the  application  of  hand  dressings  to  the  feet.  In  such 
cases  all  the  loose  and  diseased  tissue  should  be  cut  away  and  the 
affected  parts  washed  thoroughh'  with  a  5  per  cent  solution  of  carbolic 
acid.  An  antiseptic  astringent  powder,  consisting  of  4  parts  of  car- 
bolic acid,  2  parts  of  tannic  acid,  and  94  parts  of  exsiccated  alum,  is 
then  dusted  upon  the  ulcerated  surfaces,  and  a  bandage  applied  to  afford 
the  parts  the  desired  amount  of  protection. 

The  most  earnest  efforts  should  be  made  to  conquer  the  disease 
before  the  advent  of  warm  weather,  as  it  will  be  found  more  difficult 
to  deal  with  during  the  latter  period.  On  the  contrary,  cold  weather 
and  dry  seasons  are  unfavorable  for  the  development  or  spread  of  the 
disease,  although  they  will  not  cure  it. 


FOOT-ROT    OF    SHEEP.  39 


BIBLIOOBAPHY. 

(1)  Brown,  G.  T.     Contagious  foot-rot  in  slieep.     16  p.     illus.     21 J  cm.     Lond., 

1892. 
{2)  Law,   James.      Contagious    foot-rot   in    sheep    (Paronchyia  ungularis  oviuni 

contagiosa).     Vet.  jrn.,  v.  3,  no.  15,  p.  161-173.     Loml.,  Sept.,  1876. 

(3)  Francke.     Der  necrose-baeillus  als  krankheitserreger  bei  unseren  hausthieren. 

Berl.  thierarztl.  woch.,  no.  25,  p.  299-303.     Berl.,  June  22,  1899. 

(4)  Ernst,  Wilhelm.      t)ber   nekrosen  und   den    nekrosebacillua    (Streptothrix 

necrophora).      Monatsh.  f.  prakt.  thierheilk.      bd.    14,  hft.  5,  p.  193-228. 
Stuttg.,  1902. 

(5)  Hess,  il.     Die  klauenkrankheiten  des  rindes.     I.andwirth.  jahrb.  d.  Schweiz, 

bd.  5,  p.  333-365,  pi.  7-10.     Bern,  1891. 

(6)  NocARi),  ED.,et  Leclainche,  E.    Les  maladies  microbiennes  dee  animaux.    Ed. 

3,  entierement  refondue  et  consideral)le-augmentee.     2  v.     25  cm.,  Paris,  1903. 
See  V.  2,  chap.  32,  par.  HI,  p.  385,  Bacilie  de  la  n<!'crose. 

(7)  Hor.ve,  H.     Renens  klovsyge.     Norsk  veterinaer-tidsskrift,  bd.  10,  hft.  4,  p. 

97-110.     Kristiania,  1898. 

(8)  Moore,  V.  A.     The  pathology  and  differential  diagnosis  of  infectious  diseases  of 

animals.    380  p.    illus.    23  cm.     Ithaca,  1902.     See  chap.  1,  p.  13-15,  par.  10, 
Infectious  suppurative  cellulitis. 

(9)  Voces,  O.     Beobachtungen  und  studien  iiber  eine  in  Sudamerika  bei  jungen 

rindern  vorkommende  erkrankung  der  extremitaten.     Cent.  f.  bakt.,  abt. 
1,  bd.  31,  Ori„'.,  no.  4,  p.  136-141.     Jena,  Feb.  14,  1902. 

(10)  Martens.      Ueber  die  bosartige  klauenseuche  der  schafe.     Berl.  thierarztl. 

woch.,  no.  45,  p.  529-531.     Berl.,  Nov.  10,  1898. 

(11)  Martens.,    Zur  maul-  und  klauenseuche  der  schafe.     Berl.  thierarztl.  woch., 

jahrg.'7,  no.  20,  p.  180.     Berl.,  May  14,  1891. 


o 


X 


I 


UC  SOUTHERN  REGKDNAL  LIBRARy  FACILITY 


001 


126  654     1 


(Concluded  from  page  2  of  cover.) 


Dr.  C.  Loveberry,  room  402  Custom-House  (new), 
Portland,  Oreg. 

Dr.  H.  D.  Mayne,  Malone,  N.  Y. 

Dr.  Loul.M  Metsker,  room  22,  N.  T.  Armijo  Build- 
ing, Albuquerque,  N.  Mex. 

Dr.  J.  Miller,  care  John  Morrell  &  Co.,  Ottumwa, 
Iowa. 

Dr.  C.  L.  Morin,  St.  Albans,  Vt. 

Dr.  A.  B.  Morse,  care  The  Agar  Packing  Co.,  Des 
Moines,  Iowa. 

Dr.  W.  J.  Mnrphy,  care  Springfield  Provision  Co., 
Brightwood,  Mass. 

Dr.  W.  N.  Neil,  care  John  Cudahy  Co.,  Wichita, 
Kans. 

Dr.  H.  D.  Paxson,  care  Swift  &  Co.,  Fort  Worth, 
Tex. 

Dr.  F.  M.  Perry,  Fort  Fairfield,  Me. 

Dr.  G.  W.  Pope,  Animal  Quarantine  Station, 
Athenia,  N.  J. 

Dr.  H.  D.  Potter,  Calais,  Me. 

Dr.  J.  O.  F.  Price,  care  Brittain  &  Co.,  Marshall- 
town,  Iowa. 

Dr.R.  A.  Ramsay,  Fargo,  N.  Dak. 

Dr.  A.  G.  G.  Richardson,  707  Empire  Building, 
Knoxville,  Tenn. 

Dr.  A.  E.  Rishel,  care  Cudahy  Packing  Co.,  Los 
Angeles,  Cal.  ■■ 


Dr.  W.  H.  Rose,  18  Broadway,  New  York,  N.  Y 

Dr.  F.  L.  Rus.sell,  Orono,  Me. 

Dr.  J.  F.  Ryder.  141  Milk  St.,  Boston.  Mh.«s. 

Dr.  E.  P.  Schaffter,  care  Cleveland  Provision  Cu.. 
Cleveland,  Ohio. 

Dr.  C.  A.  Sehauffer,  134  South  Second  8t„  Phila- 
delphia, Pa. 

Dr.  Thos.  W.  Scott,  care  The  Rath  Packing  Co.. 
Waterloo,  Iowa. 

Dr.T.  A.  Shipley,  care  T.  M.  Sinclair  <fe  Co.  (LUl), 
Cedar  Rapids,  Iowa. 

Dr.  N.  C.  Sorensen,  care  Kiugan  <&  Co.,  Indian- 
apolis, Ind. 

Mr.  Wra.  H.  Wade,  Animal  Quarantine  Station, 
Halethorp,  Md. 

Dr.  H.  N.  Waller,  109  West  Forty-second  St.,  New 
York,  N.  Y. 

Dr.  G,  W.  Ward,  Newport,  Vt, 

Dr.  B.  P.  Wende,  Live  Stock  Exchange  Building, 
E«.st  Buffalo,  N.  Y. 

Dr.  W.  H.  Wray,  34  Streatham  Hill,  London, S.  W.. 
England. 

Dr.  C.  H.  Zink,  care  Western  Packing  Co.,  Denver 
Colo. 


DAIRY  INSPECTOR.^. 


W.  D.  CuUyer,  210  South  Water  St.,  Chicago,  111. 

James  Hewes,  1820  North  Charles  St.,  Baltimore, 
Md. 

M.  W.  Lang,  Department  of  Agriculture,  Wash- 
ington, D.  C. 

E.  A.  McDonald,  58  and  59  Downs  Block,  Seattle, 
Wash. 


I  Wm.  E.  Smith,  168  Chambers  >i.,  New  York,  N.  Y. 

B.  F.  Van  Valkenburgh,  168  Chambers  st.,  New- 
York,  N.  Y. 

Levi  Wells  (Bradford  County),  Spring  Hill,  Pa. 

G   M.  Whitaker,  P.  O.  lx)x  1332,  Boston,  Ma,ss. 

W.  D.  McArthur,  114  California  St.,  San  Francisco, 
Cal. 


^ 


